In the Amazon Prime series Bosch, there is a scene where Detective Harry Bosch uses a deceased person’s finger to unlock their phone. It might seem chilling at first glance, but there’s no need to worry. This method only works in the show, not in real life. In reality, it’s not so easy. Once a person dies, the fingerprint loses its electrical charge. This makes it impossible for a phone’s fingerprint sensor to recognize it and unlock the device.
Fingerprints are part of our daily life. We use them for everything, from driver’s licenses to unlocking phones. But what happens to our fingerprints after we die? How durable are they?
Do Fingerprints Change After Death?
Many people believe that fingerprints are unique and unchanging throughout a person’s life. However, research suggests otherwise. As time passes, the reliability of fingerprint recognition decreases. This indicates that fingerprints may change slightly over a lifetime. 
That said, it’s still possible to reliably identify fingerprints from people who are recently deceased or whose bodies have been well-preserved. For the deceased, it may require forcibly straightening the stiff fingers. Special tools may also be needed to collect the prints.
For bodies that have started to decay, dry out, or have been submerged in water, the situation becomes more complicated. However, it is not impossible. Forensic experts can remove the hands or fingers and send them to a lab for advanced processing. In cases of severely degraded skin, silicone molds can be made to capture the fingerprint patterns. These molds can still be useful for identification.
Advancements in Post-Death Fingerprint Extraction
Scientists have made significant progress in extracting fingerprints from deceased individuals. In 2013, a study published in the GMS Journal of Interdisciplinary Plastic and Reconstructive Surgery introduced a technique known as “corpse processing”. This method involves extracting fluids from other parts of the body. This helps restore the firmness and volume of the fingers, making it easier to collect fingerprints.
The study involved 400 bodies at various stages of decay. About three-quarters of the bodies provided usable fingerprints for automatic identification systems. In 11% of cases, the fingerprints were clear enough to exclude potential matches.
Though research on how long post-death fingerprints remain usable is limited, some studies show that biometric data can still be extracted from bodies up to four days after death in warm climates. In colder weather, data can be retrieved from bodies up to 50 days after death.
Conclusion
In conclusion, although fingerprints can still be used for identification after death, they cannot unlock devices like phones. This is because the electrical charge that makes unlocking possible disappears after death. Over time, the reliability of fingerprint recognition decreases. This suggests that fingerprint patterns may change slightly throughout a person’s life.
However, with advanced techniques, experts can restore the firmness and volume of fingers. This allows them to extract usable fingerprints from bodies in various stages of decay.
