Evidenciary Forensics Collection Methods, Tricks and Tips of the Trade Options

[longtabber PE]

In response to a request by Melissa ( I did promise her I would ask people I deal with and put this information out and I never break a promise to a lady) and for anyone with general interest in the techniques, I'm putting up this thread. I've contacted a few people for their input ( not all have answered yet) so what I post here isnt just my experience ( some of this is well outside my personal realm of expertise but I have over 30 years of networking and contacts- I can usually get an answer), but a compilation of techniques, experience, lessons learned and what is considered "strong evidence" ( based on a scientific and legal view as well)

I'm going to focus on what she asked specifically but I'll attempt to find out anything anyone wants to know.

Enjoy

[longtabber PE]

Forensics supplies ( This is not an endorsement of any company or product)

These are just 2 I have used over the years and if anyone has a business and opens a business account, they have good discounts.

www.spexforensics.com

www.evidentcrimescene.com

I use spex almost exclusively ( personal preference)

[longtabber PE]

Collecting Biological samples for potential DNA extraction

( Hat tip to my lab and their taking time to answer a lengthy question filled email without charging me and to an FBI guy I hunt with)

1) Cleanliness is next to Godliness regarding DNA- current methods are so sensitive that touching and even breathing on a potential sample ( that surprised me about the breathing) can contaminate a sample- use a mask, gloves and net while gathering the sample)

2) ALL specimen bags, tools etc should be ONLY ( the bags and tools such as tweezers) ones recommended for lab use and be single use and sealed until needed. Various plastic containers, tools etc are made a variety of ways and some of the platings, polymers etc will react with the sample. ( dont use just your regular sandwich bags or clean 5 gallon bucket) The equipment must be completely sterile and non reactive. ( theres an ISO and NIST standard for most of these)

3) ALL hand tools ( pliers, snips, whatever) should be bleach washed, completely degreased and boiled ( or steamed) sterile, lightly dusted with talc ( for anti rust) and sealed in a bag such as from a food vacuum sealer. You may have to cut or otherwise remove a portion of whatever the sample is on for testing and anything such as oil or whatever on a tool will likely destroy a sample if it comes in contact with it. It is PREFERRED to NOT attempt to scrape or otherwise attempt to remove a sample but when it must be done- make every attempt to "cup" liberally underneath the sample rather than trying to scrape it off of the surface.

4) Reagents- test the suspected sample with a reagent to ensure its a biological before gathering ( there are kits for this)

5) Dry samples- it is STRONGLY recommended to NOT make any attempt to rehydrate a sample in the field. ( the preferred method is to remove the artifact and let the lab do it) but if its a must, use ONLY sterile water designed for this purpose from a sealed ampoule. ( blood and other media tend to separate when being absorbed and improper hydration can damage a sample)

5) Packing samples for shipment- the preferred method of sample preservation for shipping- is to air dry them with a blower ( or hair dryer, commercial dehydrator on LOW heat- you want the air flow to wick away moisture, not too much heat) as moisture in the bag may not be sterile and may attack the sample.

6) million to 1 shot here ( the agent told me this has been done- but its a shot in the dark)- in the event theres a print that could possible have skin residue or anything else- get the filter ( from the supply house) and use a clean/sterile vacuum ( cleaned as described above) and lightly vacuum the print paying attention to the heel and toe areas ( most likely points) and send the filter and contents off .

more later- still waiting on other answers to questions

[longtabber PE]

Just curious- is this along the lines of what people seemed to want?

[Yetifan]

It seems pretty thorough to me, longtabber. Thanks for taking the time to post it.

[Mon0705]

Just curious- is this along the lines of what people seemed to want?

Sorry, I was going to chime in here earlier. Thanks for taking the time to start this thread and for collecting a few things to get this started.

From personal experience in DNA work, it seems pretty thorough. Oddly enough breathing and hair cause more contamination than you'd expect.

[oregonfooter]

good information! I can say it's what I want, and I'm sure others too.

I third the thanks.

[longtabber PE]

Sorry, I was going to chime in here earlier. Thanks for taking the time to start this thread and for collecting a few things to get this started.

From personal experience in DNA work, it seems pretty thorough. Oddly enough breathing and hair cause more contamination than you'd expect.

>>>From personal experience in DNA work, it seems pretty thorough. Oddly enough breathing and hair cause more contamination than you'd expect.

I wont lie- that one shocked me- I understand hair and stuff from my work, I never would have thought to even consider breath as a contaminant.

Still waiting for more

ETA- Its not like I know everything ( i dont) but a large part of my job is finding out what I dont know from people who do know.

I'm working on several other topics for this ( in response to my promise to melissa) and I'm going to rush them in because I'm warping out of orbit Sunday coming. ( back tu deh Ahlands Mahn so I'll be at the mercy of 3rd world internet service till Christmas)

This post has been edited by longtabber PE: Nov 27 2007, 02:11 PM

[longtabber PE]

More DNA tips from those who know a lot more about it than me ( some of these are longshots but luck does count)

1) NEVER put labels and or writing IN the sample container ( bleaches in the paper process and the inks will attack the sample) this is in response to enlightening me that this used to be a taught practice in places.

2) When scanning the area for potential samples ( urine,blood, saliva, semem etc)- a UV light can ( emphasis on can) aid in detection of possible sample

3) should a track with green foliage ( such as leaves) in the base be detected- its POSSIBLE to gain skin cells from the foliage. ( it was explained to me that green [ as opposed to dry] have a tendency to catch cells in their grain structure. Another longshot but potential source. It was also said that pine needles would damage the sample.

4) Any suspected "thrown" objects ( such as these rocks and wood) could have DNA potential ( the coarser the material, the better)

5) a "rock" can be dusted with fine talc and may yield prints ( 2 million to 1 shot)

6) samples exposed to direct sunlight or extreme moisture or more than 30 days old ( applying to samples outside in the woods) are probably not worth collecting

7) Always check foliage within 3 feet ( either side and ABOVE) of a suspected path up to suspected shoulder level ( more from my side of investigating as this is where evidence of snagged clothing can often be found from foliage whipping)- you never know what snagged skin, hair or made a cut. ( 1000 to 1 shot)

[longtabber PE]

CASTING do's and donts ( this is a combination of standard LE and industrial methods for making castings that actually contain evidence)

1) the print itself- the first question is to answer WHY am i casting this print and what do i hope to determine as a result. ( theres more than one technique for discovery of different things- casting is not a "one size fits all" science)

A- the print itself- unless you want a representation of a hole in the ground- if a print doesnt have characteristics to evaluate, theres no need to cast it. A good visual examination is the first thing to do. "What makes this print worth casting" is the perspective to look from. If you ever hope to gain anything other than a print of a hole, dont cast prints in snow or any with standing moisture or saturated substrate.

2) the Tool Kit

hair dryer ( preferably a heat gun)- if theres no power source, dont worry about it- the ideal print is cast from a dry surface but that aint always possible.

you MUST have commercial "dust and dirt" hardner and "snow wax" ( these act as a base and keep a lot of dirt from being pulled in with the casting- you want a cast of the impression, NOT the first layer of dirt)

Talc or flourescent powders ( they highlight minor details, act as both a dessicant and a release agent)

The finest ( particulate size) casting agent you can afford

chicken wire,hardware cloth, coat hangers etc ( making a frame for thin and fragile castings)

Spreader tips

3) things to be aware of:

Dessication- drying of area

Hydration seepage- pulling of substrate moisture forming a barrier, watering down the casting agent, or washing away detail

Capillary action- this is where air gets trapped along the jagged edges of a substrate ( the edges of dirt) and doesnt allow the casting agent to fulld enter the detail and this air "moves' due to the weight and motion of the casting agent making all kinds of "squigglies"

a DIGITAL microscope ( 200X or better) ( about $150)

4) Technique

mix agent to death ( mechanical mixer with battery drill works best) then agitate it ( vibrate it) to remove as much entrained air as possible and keep that up till time to pour

1) take several pictures with the microscope PRIOR to doing anything ( put stick in ground- subsequent pictures need to be from the same location, distance and angle)

2) spray dirt hardner ( when dry take second set of pics)

3) apply powders ( best with a puffer but can use a sprayer or VERY soft,fine brush) ( take 3rd set of pics)

4) pour- there are several accepted techniques but the general idea is a gentle pour preferably from a wide trough covering the entire area with a THIN coat before filling.

5) Insert frame ( especially for thin castings)

REMOVING

The accepted way is to gently remove substrate from around and under as much as possible ( best way is with an air tank) and "roll" out starting with the thinnest part. ( that may sound backwards but you want the least pressure on the thinnest part)

What you can expect.

You will have several reference pictures so you can attempt to determine the ratio of print detail versus casting effect. ( many things will show up in the pictures the cast may not get)

your cast should be reasonably clean of substrate and require much less mechanical cleaning to see detail ( plus if you got lucky, the powder held the detail)

This ought to help people get started- there are more advanced methods and different techniques

[Apeman]

2) When scanning the area for potential samples ( urine,blood, saliva, semem etc)- a UV light can ( emphasis on can) aid in detection of possible sample

...but UV light (at the "right" wavelengths) is also used for decontamination because it can "destroy" DNA, so this might not be the best idea with certain samples even (though it usually takes extended exposure)....

This post has been edited by Apeman: Nov 28 2007, 03:04 PM

[longtabber PE]

...but UV light (at the "right" wavelengths) is also used for decontamination because it can "destroy" DNA, so this might not be the best idea with certain samples even (though it usually takes extended exposure)....

Thats correct- I should have been more specific, I stand corrected

For this purpose one must use nothing but a long wave UVA type "blacklight" in the 350-400 nm range

[Melissa]

mix agent to death ( mechanical mixer with battery drill works best) then agitate it ( vibrate it) to remove as much entrained air as possible and keep that up till time to pour

Unless your mixing a large quantity - even US Gypsum would disagree with you on this. Mixing with a latex gloved hand is the best option for what we are doing. The same instructions I was given by them, are the same instructions given to the FBI - by US Gypsum.

Otherwise, your mixing in too much air - and you can only remove so much trapped air before the casting agent sets, and then you have a mess.

Debate this all you want - but I plan to cast as accurately as possible.

I also see no mention of the fact that the casting agent needs to be added to the water - not the water to the casting agent. This is very important and should not be ignored.

What your using for reinforcement also have issues. I use aluminium fence ties, as taught to me by 2 of the finest casters I know. Chicken wire will degrade inside the cast, along with the other items you mentioned. Then you have no reinforcement

This post has been edited by Melissa: Nov 28 2007, 03:20 PM

[bartlojays]

This is great! Thanks for taking the time to do this. Although I know alot of this stuff, alot of it I don't (much we naturally forget as well).
Thanks again LT and now the Apeman coming in with the assist too!

[longtabber PE]

Unless your mixing a large quantity - even US Gypsum would disagree with you on this. Mixing with a latex gloved hand is the best option for what we are doing. The same instructions I was given by them, are the same instructions given to the FBI - by US Gypsum.

Otherwise, your mixing in too much air - and you can only remove so much trapped air before the casting agent sets, and then you have a mess.

Debate this all you want - but I plan to cast as accurately as possible.

I am aware of what is taught and what I'm telling you is the best way. The field instructions are designed for general usage. Its not a matter of right and wrong, but good, better and best.

Proper mechanical mixing is the gold standard everywhere as is agitation for settling. Ask anyone in the cement or aggregate industry. ( which International Gypsum, Portland and others who make up the consortium write the books for and are some of my customer base)

The reason they tell you about hand mixing is because most people dont know how to mechanically mix properly so they screw it up. They slop it around like a milkshake. Yet go to any plant anywhere- see what the "pros" do.

I also see no mention of the fact that the casting agent needs to be added to the water - not the water to the casting agent. This is very important and should not be ignored.

What your using for reinforcement also have issues. I use aluminium fence ties, as taught to me by 2 of the finest casters I know. Chicken wire will degrade inside the cast, along with the other items you mentioned. Then you have no reinforcement

>>>I also see no mention of the fact that the casting agent needs to be added to the water - not the water to the casting agent. This is very important and should not be ignored.

No, I didnt intend to write a short novel- i left some of it to people to actually read the instructions

>>>What your using for reinforcement also have issues. I use aluminium fence ties, as taught to me by 2 of the finest casters I know. Chicken wire will degrade inside the cast, along with the other items you mentioned. Then you have no reinforcement

After 50 odd years- is that really that important?

[Melissa]

I am aware of what is taught and what I'm telling you is the best way. The field instructions are designed for general usage. Its not a matter of right and wrong, but good, better and best.

And, I am saying based on the months (actually over a year) of work and testing I have done - your way is not the best way for people who do what we do. Attention must be paid to certain details of this process. And, yes - even after 50 years I want those casts that are deemed good enough to stand up to scrutany - to last another 50 years if possible.

This post has been edited by Melissa: Nov 28 2007, 03:42 PM

[Hairy Man]

I am aware of what is taught and what I'm telling you is the best way. The field instructions are designed for general usage. Its not a matter of right and wrong, but good, better and best.

How do you know it's the best way? Is this the method you use?

[Hominid,WA]

Good question.

[wolftrax]

Unless your mixing a large quantity - even US Gypsum would disagree with you on this. Mixing with a latex gloved hand is the best option for what we are doing. The same instructions I was given by them, are the same instructions given to the FBI - by US Gypsum.

Otherwise, your mixing in too much air - and you can only remove so much trapped air before the casting agent sets, and then you have a mess.

Debate this all you want - but I plan to cast as accurately as possible.

I also see no mention of the fact that the casting agent needs to be added to the water - not the water to the casting agent. This is very important and should not be ignored.

What your using for reinforcement also have issues. I use aluminium fence ties, as taught to me by 2 of the finest casters I know. Chicken wire will degrade inside the cast, along with the other items you mentioned. Then you have no reinforcement

And, I am saying based on the months (actually over a year) of work and testing I have done - your way is not the best way for people who do what we do. Attention must be paid to certain details of this process. And, yes - even after 50 years I want those casts that are deemed good enough to stand up to scrutany - to last another 50 years if possible.

From the USG website:

Mixing directions

Sift or strew plaster into water slowly and evenly. Do not drop handfuls of plaster directly into the water. Allow plaster to soak for 2 to 4 minutes, then mix as required - generally 2 to 5 minutes - to obtain a creaming of the slurry. Always add plaster to water, never the reverse.

Hand mix - Generally acceptable for small batches up to 5 lb. However, since optimum physical properties are in direct relation to energy input in mixing, hand mixing will not result in a plaster cast with the best properties.

Mechanical mixing - For best results, use a high-speed, direct-drive propeller mixer with mixing shaft set at an angle of 15º from vertical. The propeller should clear bottom of container by 1 to 2 in. and the shaft should be about half-way between center and side of the container. Propeller rotation should force mix downward. Keep all equipment clean to avoid accelerated set of plaster.
http://www.plastermaster.com/usg/plasterfundamentals.htm

[Bitter Monk]

As someone who had to suffer through a poorly mixed homemade icing the other night I can attest to the importance of thorough mixing. If I'm doing a two stage casting I beat the first stage like it owes me money.

When it comes to reinforcement just remember... nothing organic and nothing that will rust.

I'd also add that all pertinent information be recorded on the back (top side) of the cast via engraving before the cast comes out of the ground.

By the way, thanks for all the info longtabber.

[longtabber PE]

How do you know it's the best way? Is this the method you use?

What part of its industries "gold standard' did you miss?

[longtabber PE]

And, I am saying based on the months (actually over a year) of work and testing I have done - your way is not the best way for people who do what we do. Attention must be paid to certain details of this process. And, yes - even after 50 years I want those casts that are deemed good enough to stand up to scrutany - to last another 50 years if possible.

Working for a month or a year doesnt mean anything was ever done "right" or the "best' way to begin with

the people who 'do what we do" have a history replete with "less than acceptable" results and other "people' who do what you do at a MUCH HIGHER LEVEL were trying to help you- but once again, narrow minded arrogance gets in the way of best practices.

If you want a cast that will stand up to 'scrutiny"- then throw away everything you have now and think you know and START OVER because what you have now isnt "nothing" its LESS than NOTHING

If you want something to last forever and last 50 plus years- dont worry about the internal frame ( it just adds strength)- you better come up with a different casting media- if you want a super skeleton- forget aluminum- you need titanium

[Hairy Man]

What part of its industries "gold standard' did you miss?

What part of how do you know did you miss? You stated above that it's a mixture of LE and industrial methods...who mixed the methods? You? Someone else? Has it been tested?

[wolftrax]

2. Do I still need a power mixer just to get started?
The plaster and HYDROCAL® Gypsum Cement products made by U.S. Gypsum Company and sold by the Industrial Products Division should always be mechanically mixed with a properly sized motor and drill based on batch size and product. We have many tests which show that mechanically mixed products have the best strength and hardness. However, we do know that it is common practice to mix by hand especially in some markets. Two factors that control the effectiveness of hand mixing are batch size and water to powder ratio, which is also known as use consistency. In general, the lower the amount of water in the total mix, the more difficult hand mixing will be. This difficulty gives rise to the practice of adding excess water so mixing can be done. If this occurs, strength and hardness are tremendously reduced because there is already a reduction from hand mixing compared to mechanical mixing. Also, it is very difficult to properly hand mix a large batch of material even if the water to powder ratio is high. Slurries must be mixed with enough energy to properly disperse the powder in the water and arm strength is seldom the equal of a good motor in large batches.

http://www.gypsumsolutions.com/webQA/webQA...ng/Mixing#prob1

[Melissa]

Mixing directions

Sift or strew plaster into water slowly and evenly. Do not drop handfuls of plaster directly into the water. Allow plaster to soak for 2 to 4 minutes, then mix as required - generally 2 to 5 minutes - to obtain a creaming of the slurry. Always add plaster to water, never the reverse.

Hand mix - Generally acceptable for small batches up to 5 lb. However, since optimum physical properties are in direct relation to energy input in mixing, hand mixing will not result in a plaster cast with the best properties.

Mechanical mixing - For best results, use a high-speed, direct-drive propeller mixer with mixing shaft set at an angle of 15º from vertical. The propeller should clear bottom of container by 1 to 2 in. and the shaft should be about half-way between center and side of the container. Propeller rotation should force mix downward. Keep all equipment clean to avoid accelerated set of plaster.

Yes, that is in essence exactly what I said - right up until the mixing. How many researchers in the field carry with them a high-speed, direct drive propeller mixer - hell, how about just the juice to run it in the field??

Which is exactly why hand mixing in this situation is the best alternative. Using anything smaller than a paddle or your hand will create too many air bubbles - and give you artifacts.

This post has been edited by Melissa: Nov 28 2007, 05:44 PM

[longtabber PE]

What part of how do you know did you miss? You stated above that it's a mixture of LE and industrial methods...who mixed the methods? You? Someone else? Has it been tested?

I mixed the methods ( and i was referring to the techniques rather than the actual chemistry)

Yes, its been tested, millions of times for over a century. The standards are global.

I "know" because i deal with castings and aggregates all the time( and i'm stamped to approve and test them) ( thats a large part of what NDT is)

I'm glad i was warned about this.

This is what happens when ego meets reality

Here are some factoids for you and Melissa

1) mixing an aggregate is paramount for uniform consistency, strength and quality

2) mechanical mixing is the UNIVERSAL accepted "best practice"

3) mechanical agitation is the UNIVERSAL recommended method for removing entrained air

It makes no difference whether you are casting a print or pouring a building- the laws applying to aggregates dont change ( polymers are a wee bit different but not much)

I hope this helped you out.

[Hairy Man]

An excellent and detailed article on the methodology on finding and casting suspected bigfoot prints was written by Rick Noll in 2001. It can be found here. It is the method I use in the field because it's practical.

[longtabber PE]

Yes, that is in essence exactly what I said - right up until the mixing. How many researchers in the field carry with them a high-speed, direct drive propeller mixer - hell, how about just the juice to run it in the field??

Which is exactly why hand mixing in this situation is the best alternative. Using anything smaller than a paddle or your hand will create too many air bubbles - and give you artifacts.

Its not hard to carry a BATTERY DRILL with a mixing blade ( the battery has the "juice' in it)- again i offered the BEST method- not the method the technically challenged are stuck with

Hand "mixing' isnt the "best" of anything- if you believe that, "hand mix' your next cake

I respectfully recommend you dont critique things you have zero understanding of

[Hairy Man]

I mixed the methods ( and i was referring to the techniques rather than the actual chemistry)

Yes, its been tested, millions of times for over a century. The standards are global.

I "know" because i deal with castings and aggregates all the time( and i'm stamped to approve and test them) ( thats a large part of what NDT is)

I'm glad i was warned about this.

This is what happens when ego meets reality

Here are some factoids for you and Melissa

1) mixing an aggregate is paramount for uniform consistency, strength and quality

2) mechanical mixing is the UNIVERSAL accepted "best practice"

3) mechanical agitation is the UNIVERSAL recommended method for removing entrained air

It makes no difference whether you are casting a print or pouring a building- the laws applying to aggregates dont change ( polymers are a wee bit different but not much)

I hope this helped you out.

There is no ego about it, except yours. I just asked you a simple question and you chose to answer it with attitude. I didn't say a thing about aggregate or mixing method...you stated the method was a mixture of methods between LE and industrial and I was curious who mixed the methods. Chill out...

[longtabber PE]

There is no ego about it, except yours. I just asked you a simple question and you chose to answer it with attitude. I didn't say a thing about aggregate or mixing method...you stated the method was a mixture of methods between LE and industrial and I was curious who mixed the methods. Chill out...

OK, i was aggrevated by someone else- not you

I stand corrected and offer you my fullest and sincerest apology. i was wrong in my post to you.

An excellent and detailed article on the methodology on finding and casting suspected bigfoot prints was written by Rick Noll in 2001. It can be found here. It is the method I use in the field because it's practical.

When did Rick Noll become an expert? What are his credentials?

more importantly, what are his RESULTS?

[Melissa]

And people wonder why we are beat up and called unprofessional.

This is why. You are using outdated information - I say outdated, because people stopped using chicken wire in casting material a very long time ago for this, hell Im shocked you didnt recommend the use of a popcicle stick.

I think it is you who does not know what your talking about. As my methods have proven results, and I have only seen artifacts when I deviate from the methods I discussed in this thread.

[Hairy Man]

OK, i was aggrevated by someone else- not you

I stand corrected and offer you my fullest and sincerest apology. i was wrong in my post to you.
When did Rick Noll become an expert? What are his credentials?

more importantly, what are his RESULTS?

Apology accepted.

Trust me when I say all anyone wants is the best methods to collect the best evidence possible.

Rick Noll can provide more info, but I believe he works in aerospace engineering and with casts and casting materials daily.

[longtabber PE]

Apology accepted.

Trust me when I say all anyone wants is the best methods to collect the best evidence possible.

Rick Noll can provide more info, but I believe he works in aerospace engineering and with casts and casting materials daily.

>>Apology accepted
Thank you

>>>Rick Noll can provide more info, but I believe he works in aerospace engineering and with casts and casting materials daily.

I have customers such as NASA, Gulfstream and a few others ( ga Gulfstream)- they dont do much casting as everything they do has to be machined so I'm curious as to where casting is applicable to his career field or his expertise is related to it.

But, I suppose i need to talk to him. it wont take but a few questions to see.