9 BURNT HAND FINAL.mp4 — 515888 KB
Bryan T. Johnson, Major Incident Program Manager, Latent Print Unit, FBI Laboratory Division: Welcome to another installment of the Postmortem Fingerprinting video series.
In this video, we discuss how best to approach and print burned cases. Oftentimes, when a case is brought in that has thermal damage, fingerprints are not attempted based solely on visual cues. While the outside of the hands may look very damaged and bones may be exposed, often there is still viable skin left to be able to be printed on the inside of the hands. The hands are very resilient, and it is not uncommon for the fingers and palms to be partially protected due to the way muscles contract and respond to high degrees of heat. We hope that after you watch this video, you will feel confident to try and print every case that still has hands present, even after vast thermal damage.
Lastly, we would like to thank the District of Columbia Office of the Chief Medical Examiner for their collaboration and participation in this series, ensuring that everyone watching is provided with the tools needed to identify unknown, deceased everywhere.
When presented with a burn case, the first step is always to gently inspect the extent of the fire damage to the hands. Traditionally, fire affects the outside of the hand the most, and the natural process of the heat tightening the tendons and muscles protects the insides of the fingers longer than the rest of the hand. As the body compresses into the pugilistic pose from the shortening of the tissues, it causes the fingers to retract into closed fists. The fingers become very difficult to move, and unlike rigor mortis, they do not actually bend back without breaking the joints or cutting them.
On this hand, the palmar skin has started to separate and pull away, which is different than traditional sloughing seen with decomposition because it is only caused by heat and not by bacteria. The epidermis, which is the outer layer of skin, will often harden and feel plasticized. To process this hand, each finger will be worked on individually to see if the fingers were protected enough to still obtain usable fingerprints. When examining a burned hand or finger, it is imperative not to initially touch the end joint of the finger. They can become brittle and shatter or break under pressure. If the fingers are severely burnt, they will snap off if they're bent backwards even slightly. In this case, it may be best to photograph or remove the digits to process by cutting the third joint where the finger meets the palm.
All fingers have three possible ways of being printed: the outer epidermis, which is what is used antemortem and for most deceased cases; the inside of the epidermis, if it can be removed; and finally, the dermal layer underneath, again if the epidermis can be removed. Absent decomposition or fire, the epidermis should not be removable. In fire cases specifically, it is also important to consider the use of photographic capture along the way in case the actual printing methods do not yield a viable print.
In this photo, the outside of the epidermis is seen after being removed. There is fire damage to the pattern area of the print, and while this print still may be usable, it is the first surface to go in thermal cases. Next, this photo shows when the epidermis is turned inside out after being removed. The skin has been placed in duct seal to allow it to be photographed easier. This capture will be in reverse position or mirror imaged, but as long as it is noted on the capture, this can be one of the best ways to identify a burn victim. Even when there is fire damage to the outside of the epidermis, the ridge arrangement is often unharmed on the inside.
Depending on the temperature of the fire and severity of the thermal damage, the epidermis may be completely compromised. The heat may also assist, however, in causing the epidermis to separate completely. In this photo, the dermal layer of the finger is seen after being cleaned up. The dermal ridges are just two rows of pegs that hold up the epidermis in the same friction ridge arrangement. With minimal effort or even possible boiling, the dermis can be photographed or printed as well.
After rehydrating the dermis, it can be printed with powder and adhesive lifters, yielding a very highly usable postmortem print. This can be done for all of the fingers and be sent to a fingerprint examiner for processing. If the epidermis is still intact or present, making a gentle incision around the outside of the finger will allow it to be separated.
Once the incision is made to separate the skin layer, a method called break and twist will allow the skin to be pulled off the finger like a glove. If the skin will not fully come off, additional fine incisions will assist the practitioner to get it off without tearing. If the skin cannot be used due to obvious thermal damage, it can be peeled off so that the dermal layer can be exposed. Note the inside of the epidermis may still be very usable, even if the outside is charred and bubbled. The use of a dental pick or other fine metal tool can help get the remaining epidermis to separate and expose the dermal layer. The fingers should then be thoroughly cleaned with alcohol or acetone to prepare it for printing. Because the dermal skin has very fine rows of double ridges, black powder and a vinyl lifter should be used to capture these prints.
To see if the finger can be printed without any additional reconditioning or rehydrating methods, a thin layer of black powder is applied, and a vinyl lifter is used to capture the dermal bridges. In these cases, it is important to use the adhesive sticker rather than the ink and paper method, because the higher resolution of the sticker is necessary to capture the dermal prints. The sticker should be gently applied and then rolled around the finger.
Commonly the first lift will come off with additional tissue still attached, even if the finger was already cleaned. The tissue can be removed from the lift with forceps or a pointed object, taking care not to disrupt the recording. If the tissue is not impeding the recording, or if it would damage the lift to remove it, it can be left on and adhered to the acetate. The finger can then be reprinted without applying any more powder.
It is important that all recordings taken for the finger be kept, as each one may have different parts of the print captured more clearly than the next. When using an acetate, each recording should be labeled as to which finger it is from since there are not enough finger blocks on the acetate for multiple captures of the same finger.
After printing the dermis, the previously removed epidermis can be examined to see if it is printable or can be photographically captured. There is often still moisture trapped between the layers, even though it was burned, so it is important to dry and clean the underside of the epidermis before attempting to print it. The same powder and lifter method is best for this technique as well. Again, alcohol or acetone can help quickly dry it, or even a hair dryer can be useful if available. Be careful when attempting to use a hair dryer that there are not loose particulates still on the skin that can be problematic and messy. If the skin is not quite dry, simply fanning air onto it or gently waving it can also assist. It is imperative that it is dry to keep the powder from clumping up.
Once the powder is applied, the use of a duct seal mold helps give three dimensionality structure to this skin and allow it to be printed more naturally. It also can hold the lifter in place so that the skin can be handled with care.
As shown in the beginning, this is a photograph of the underside of the epidermis. Even if the skin doesn't print well on either side, a clear scaled closeup photo of the skin showing the ridges can be used in search for identification purposes. When printing the underside of the epidermis, it needs to be labeled as such on the acetate because it will be in reverse position. If it is not accurately labeled, it will not be properly searched and may result in a false exclusion.
Once the first finger has been fully printed, the next step is to start on the other fingers and repeat the same process. Minimally, the thumbs and indexes should be printed, if possible, as that will ensure all databases are searched. All ten fingers are best to capture because that will ensure the greatest accuracy of the searches.
As before, the dental pick or similar tool can help with sliding the epidermis off, taking care never to poke or cut the underlayer in the process, as it would damage the fragile dermis layer. Once the skin is removed, it will need to be cleaned and dried as before. It is important to keep track of the different epidermal skin pieces that are removed by tracking the finger that they are from. This can be done with pre-labeled jars or even a numbered grid on a paper towel. It is just as important that all of the skin and debris be placed back inside the body bag at the end of printing.
Upon inspection, the moisture and fire residue must be cleaned from the underside of the epidermis before printing. While the epidermis is drawing, the dermis of the second finger can be inspected and cleaned. In order to gain access to the finger for printing, shallow incisions are made into the creases of the lower joints, allowing them to bend. Due to the tightening of the muscles, the finger will not bend without releasing them.
The finger can be accessed for printing but does not have to be removed from the body. This hinge principle can be especially helpful when the fire damage is much worse and the fingers have no pliability at all. Note that all cutting, removing, and altering of the hands should be done with explicit pre-approval from the medical legal authority.
The alcohol wipe left behind some fibers that must be removed, or they will inhibit the ability to capture the print. Once removed, the black powder can be applied and the print taken. Looking at the prints taken so far, it should be obvious that they are much smaller in size than normal prints would expect to be. Fire damaged fingers and skin can shrink down to as much as 50 percent of their original size. The fingerprint card should always include a note that it was taken from a burned body because the fingerprint expert can make this adjustment in size when searching the prints.
Again, the inside of the epidermis is powdered and printed with the assistance of duct seal. Note that an intentional dimple has been made into the ring of duct seal to allow the skin to curve into the lifter. The skin is gently pressed evenly against the sticker so that the print is left behind. The lift is added to the acetate and then labeled.
Throughout this case, the outside of the epidermis has been damaged from the fire on all fingers. Therefore, there was no attempt to print that part of the skin. The process is repeated down the line with the remaining fingers on the hand. The next finger's epidermis is able to be removed without cutting or dental tools. Each finger will be slightly different based on the amount of heat it was exposed to and how well they were protected. This sequential printing process continues until they're all printed to the best they can be, and then the process can be repeated with the other hand.
On the next hand, the epidermis on the palm was plasticized and burned beyond use, so it was removed to allow the palmar dermis to be printed. The dermal bridges were protected from the fire by the epidermis, and they could be easily seen visually.
As the practice of collecting palm print records during arrests increase throughout the U.S., the need to collect them during postmortem printing becomes more important. This is also a helpful tool when the fingers are compromised or in disaster situations where the hands may be severed into multiple disassociated portions. The actual process of collecting the palm prints does not differ much from the collection of the fingerprints. The cards or vinyl lifters used just have to increase in size, and it may be helpful to have a second practitioner available for boiling or particularly difficult cases.
After the hand is cleaned with alcohol wipes and then dried, it can be printed using powder and a vinyl lifter. The dermal ridges often will not show up using ink and paper, and the higher resolution of the powder and lifter will alleviate this issue. The fingers can still be printed after the palm print is taken, but since usable prints were taken from the other hand, the focus on this hand is to capture a high-quality palm print.
As the powder is applied, it is important to look and see if it is clumping up. If it is, then likely there is still excess moisture on the hand. The hand can simply be wiped off, and then without adding more powder, the brush can be used to redistribute it evenly along the surface. Likewise, if the first lift is really dark, then simply take another without adding additional powder, and it will likely solve the issue.
When capturing palm prints, it is important to capture from the bracelet crease on the wrist all the way up to the fingers as much as possible. The lift is seated at the base of the wrist, and then even pressure is applied to ensure that the lifter touches the hand firmly but does not touch multiple times. Multiple impressions will often render the capture useless.
Once all of the surfaces have had pressure, it can be gently and evenly peeled back off. The final result can then be sealed and preserved by placing an acetate sheet over the top of it. The lift should be labeled with appropriate case information, as required by the agency's SOPs.
Once the epidermis has been processed to the fullest extent and an attempt at printing the dermis has been made, the final process to get a usable print is to boil the hands for five to ten seconds, and then immediately reprint them. This rehydration process will often result in the best recording, but since it can be damaging to the hand if there any wounds or the fire damage was extensive, it should always be done after all the other attempts are made.
Once the hand is boiled, the hand will only be re-printable for the next three to five minutes before the dermal ridges dehydrate again. For this reason, it is important to be ready to print before starting the boiling process so there is sufficient time to capture the prints. Boiling the hands multiple times can cause the fingers to drastically shrink and the prints to be ruined. The same process of powdering and lifting is used after boiling to record the fingerprints. The recordings can be saved onto the same acetate as long as they are appropriately labeled for finger number.
Once the first hand has been fully printed post-boiling, the other hand can also be triaged and boiled. Since this hand had more extensive fire damage, it will be necessary to cut hinges into the finger joints to be able to accurately access the fingers. The epidermis on this hand was not in the same usable shape as the other hand, so the remaining fragments of the skin can be gently removed.
If the fingers are somewhat pliable similar to rigor mortis but will not release, one option is to do a Siwek slice. Published by Donald Siwek at Boston University, this technique allows the tendons in the wrists to be severed so that they release the fingers. If the fingers have hardened into place, this will not be effective, but if the only issue is battling the tightened tendons, this can release all the fingers at once.
The alternative is to cut each of the finger joints independently to create a hinge. Note that before cutting the wrist to this magnitude, permission from the medical legal authority should be obtained as not to interfere with other investigative needs. The finger joints can be cut with a scalpel, making tiny incisions into the natural joints just deep enough to allow the finger to bend backwards. Finally, after releasing the joints, the remaining epidermis still attached can be removed and processed for possible printing. The end goal will be to expose the dermal layer and prepare it for printing and boiling.
As the finger epidermis is removed, it is still important to place it either in labeled jars or on a paper towel with a numbered grid so that if it is printable, the origin is tracked. The fingers are then cleaned, and printing is attempted using the powder and vinyl lifter. The gridded paper towel is moved to a flat surface, and the removed epidermis is placed into the appropriate column. Powder is again gently applied to the finger.
As can be seen on the white background, a decent amount of debris will continue to shed off. This will also likely impede the first vinyl lift taken. The benefit of using the individual lifters is that multiple lifts can be used without messing up a full ten print card. Without powdering, a second lift can be taken, which will have less powder and less debris. Unless there are no ridges seen on the lift at all, all recordings can be kept and submitted for comparisons as long as they are appropriately labeled.
The remaining fingers can now be assessed to see if the epidermis is viable. On this hand, the epidermis has been greatly compromised by the fire, so the remaining skin is removed to expose the dermis. The skin can either be peeled off or gently scraped off using the blunt side of a dental pick. If ridges are seen on the epidermal pieces being removed, they can be cataloged on the grid for later processing. If they are not, then it is important to ensure that all removed skin stays with the remains.
As the final skin is removed with the dental tool, it is important to note that without decomposition or perimortem changes such as fire or postmortem subversion, the dermis and epidermis will not just separate. They are naturally adhered tissues, and it is not possible to separate skin normally without chemical processing or further decomposition. The dermal skin is now printed prior to boiling in case there are any detrimental changes from the boiling process. Boiling the hands will rarely, if ever, help with rehydrating the epidermis, so it should be reserved for exposed dermal skin.
A second lift of the finger is taken without applying additional powder, in case there were any other debris impeding the first recording. While the water heats to a boil, the few pieces of epidermis that were saved can be cleaned and printed using the powder and vinyl lifter. The lifts can then be added to the same sheet that was used for the finger. If the hands deglove or the skin falls off into the body bag, it is advisable not to try and label it based on the assumed finger, but rather to just mark it as an unknown finger. The degloved skin should also be treated as separate remains to the attached hands until identified if more than one individual was involved in the death.
Now that the dermis is exposed, the hand can be boiled briefly. A burned hand does not typically need as long of a boiling interval as a macerated hand would, so five to ten second intervals are appropriate. It is important to make sure all the fingers are submerged, and having a second technician available for this step can be very beneficial.
The hand should be thoroughly and quickly dried using a paper towel or absorbent cloth. The dermal ridges will be rehydrated and viable for the next five to seven minutes, so it is important to be ready to execute the printing process as soon as it dries. The fingers and ridges will be somewhat fragile, so the fingertips should not be squeezed heavily if at all possible.
The final recordings of the fingers post boiling can be taken and added to the acetate sheet. All the impressions gathered should be scanned at a minimum of 500 PPI or photographed with a one-to-one macro lens and a scale and submitted for identification. A standard fingerprint loop or magnifier can be a valuable tool for a practitioner. The person does not need to be an experienced fingerprint examiner to look at the prints. The goal is to ensure that the prints look clear without drag or smear marks. Reprinting can be done where necessary.
Finally, the boiling of the fingers cause the remainder of the epidermis on the palm to detach. The skin can easily be pulled off and placed back with the rest of the remains. Since the dermis is now exposed, a quick cleaning and printing is done to record the palm print on this hand as well. Note that the palmar epidermis has shriveled up and is dissolving. It would not even have been viable to photographically capture.
The vinyl lift can simply be placed on the hand and pressure applied to capture the palm. Alternatively, the lift can be placed on the gurney and the hand pressed onto it if the remains can be manipulated as such.
At the end of printing, here's an example of a card created for one hand of this case. Because multiple impressions were taken of each finger and retained, they were labeled as such on the card. It is okay to still use a 10 print card template for this, as long as it is labeled appropriately. The card will have notes added that state the deceased was burnt and that these are dermal prints to assist the fingerprint examiner in their comparison and searching. All applicable photos and lifts taken should be submitted to the proper agencies for identification.
Here is a closeup of one of the dermal impressions taken. Note that it is not an impeccable quality print that you would expect to see from an antemortem record, but it is clear and identifiable.
Lastly, regardless of the fire damage done, the process to attempt fingerprints is the same. These last two photos show much worse thermal damage on cases that were still printed and identified using the same steps. If there are still hands present, all of these steps should be followed to give the practitioner a chance to identify the deceased.
In this video, we discussed how to triage and attempt printing on a burned case. While thermal damage can render the hands unprintable or even cause them to be consumed by the heat, they are often more printable than many would expect. It is important in these cases to take extra time, being tenacious and patient. Due to the way the human body reacts to heat, a case should not be passed on just because thermal damage is seen. An identification can be made with just one finger if the recording is good enough. So even if the other nine fingers are unprintable, it still may lead to an identification. Also, it is important to capture palm prints even if the fingers are compromised, since many agencies have started collecting them antemortem and they can be searched in databases just like the fingerprints would have been.
Hopefully after watching this video, you have a better understanding of what can be done to help obtain prints from even the most difficult of cases. By having these tools and others available to your office, you can ensure that no one goes without a name. We encourage you to watch the remaining videos in this series so that you may learn additional rehydration and reconditioning techniques that can further assist in obtaining the prints needed to identify the deceased. We also encourage you to reach out to the FBI Laboratory with any questions you may have regarding this content or any case related questions we may assist you with.