Boiling Rehydration Method

Possibly the most underutilized tool in postmortem printing, this technique can assist with macerated, post-hydroxide rehydration, and even burned remains.

video/mp4 6 BOILING POT FINAL.mp4 — 126333 KB

Video Transcript

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 will address a method called the boiling technique. This demonstration will be a continuation of identifying the decedent previously processed for the degloving technique video. To track the steps that led to the condition of the hands up to this point, please feel free to watch that segment first.

The boiling method is a very useful technique that has changed the way we process macerated remains or any decedent that has been in the water for extended periods of time. It is also frequently used in mass disaster events when the remains may take longer to process than individual cases would.

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.

The first thing to discuss before boiling is the type of pot being used. A boiling pot that lifts off the base is much more functional when working next to a gurney that may not be near an outlet. Pots that have to stay plugged in are limited by the length of the cord, which can be very difficult to work with if processing more than one body or multiple rounds of boiling are required. While pouring boiling water into a pan or container can also work in a pinch, having the right equipment can make the task much more efficient and effective. It is also important that the opening of the top actually allows for a full size hand to go inside the pot. If the opening tapers and the hand doesn't easily go inside, irreversible damage can be done while trying to insert it, so there is no specific brand or type of boiling pot required as long as it can boil water and fit the decedent's hands.

Now that the water is boiling, it doesn't have to continue to boil, but it should be at or near a boiling point when being used. If more than a few minutes pass, it'll be necessary to get the water temperature back up to near boiling. It is also important in this process that you're ready to do the next step of printing the fingers as soon as you boil them as the effects of doing this only last three to five minutes, and then the ridges start to dehydrate again. The boiling process can only be repeated three to four times, so it must be printed immediately.

Anatomically, the hand will not easily go into a boiling pot when the deceased is laying in the supine position. Rather, bend the elbow and follow the natural muscular progression over the shoulder so that the wrist and fingers point downward into the pot. Lower the hand slowly into the water and count 10 to 15 seconds. Observe and make sure that the water does not accidentally overflow from displacement.

Again, this process can only be repeated three to four times before it no longer has an effect and eventually damages the skin. Remove the hand and examine the fingertips for friction ridges. Note that the color is back, and the rigidity or stiffness of the fingers has returned. For this case, only one round of boiling was necessary to achieve usable dermal ridges.

The next step is to dry it, noting that the heat from the boiling water will actually speed up the drying process. No alcohol or acetone should be necessary this time. The now rehydrated dermal ridges are ready to be printed. It is important in this case to always use fingerprint powder and lifters for quality rather than ink and paper. The double rows of dermal ridges that will be recorded will not usually be strong enough to print cleanly on paper. Looking back at the prints taken during the degloving method, no ridge detail was recorded from the dermal skin.

Now that the finger was printed again simply after being boiled, there are not only fingerprint ridges, but it is a good quality identifiable fingerprint. While the epidermis didn't work because it was degloving and decomposing, removing the epidermis and boiling the dermis to get its structure and rigidity back allowed us to print it in an identifiable way.

Just as before, if the print can be improved, taking another recording while the ridges are still rehydrated is always a good idea, especially for dermal recordings. In a typical case, all of the fingers would've been degloved prior to boiling because all of them should be printed when submitting for identification. While a single finger can be identified, having all the fingers recorded greatly speeds up the process and likelihood of that identification being made.

The interesting thing that boiling does is that it can also take the epidermis that is nearly sloughing but still adhered and finishes the sloughing process. If needed, the hand can be boiled and then the epidermis fully removed. It will not take a non-sloughing hand and cause it to slough, however. The dermis may require being boiled again once exposed. The boiling method is only intended to rehydrate the dermal skin and can stretch out epidermis or greatly increase the size of any defect, wound, or cut.

Printing the boiled epidermis, it can be seen that the pores in the skin are much larger and the recording is also larger. Seen here was the original ink and paper versus the recording after boiling, powdering, and using an adhesive lifter. The quality goes from not usable to very much identifiable. It is still not an amazing fingerprint, but given the condition of the body, that is to be expected on epidermal skin.

This photo is another example of before and after the boiling technique. It truly shows the drastic difference that can result just from the boiling water. The ink print was before boiling and is not usable. The powder print was easily identified, even though it is a dermal print. The fine double rows of dermal ridges can be seen in the lower prints, but the information is still the same.

The boiling method is a tried-and-true way to take a hand considered unprintable with no visible ridges and to rehydrate it so that it is easily printed. This technique is easy, affordable, and the required equipment can be purchased from most major department stores. It is important to remember that boiling will help the dermal layer but will not help process hands that still have intact connected epidermis. It is also good practice to label the card for any recordings that are taken with the techniques used so that the person examining the prints knows what they're looking at and can account for any changes it may have caused. Different postmortem changes and printing techniques can alter the fingerprints from as much as 50 percent smaller to 150 percent bigger in size, and this needs to be accounted for when searching databases for unknown deceased.

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.