All of us will die at some point. Unfortunately, some individuals pass away in circumstances that make it difficult to determine their identity.
When a person can’t be identified after death, they are often referred to as a Jane Doe, John Doe, Unidentified Person, or Unidentified Decedent. Finding out who they were in life is important for a myriad of reasons – from assisting legal proceedings to bringing closure to loved ones.
So, how can we find out a deceased person’s identity?
Identity verification using DNA
As DNA is unique for the vast majority of people, analyzing it is an obvious route for identification.
“Sometimes you can get good identifiable autosomal DNA: DNA from chromosomes other than sex chromosomes,” Professor of Forensic Genetics at King’s College London Denise Syndercombe Court tells IFLScience. “But you can only do something with that if that person is on the DNA database.”
Being on these databases is often a result of a person coming to police attention, and this isn’t the case for everyone.
“If the body has remained unidentified for a long period of time, the police may go down what’s called a familial search, looking for either parents, children, or full siblings of the deceased in the criminal records,” Professor Syndercombe Court explains.
Sometimes, family members of missing people giving DNA samples voluntarily can lead to the identification of a body. One notable case is the recent identification of Francis Wayne Alexander, murdered by serial killer John Wayne Gacy in the 1970s. His remains, alongside those of other unidentified victims, were exhumed in 2011 alongside a call for relatives of men who went missing in the 1970s to submit DNA.
DNA was extracted from one of his molars, which then underwent whole genome sequencing. Samples from Alexander’s half-brother and mother were a strong match, confirming his identity decades after his death.
DNA can also be used to estimate a person’s age when they died, potentially narrowing down candidates for who they are.
“We look at small changes on the DNA. So the DNA molecule doesn't change, but small chemicals get stuck to it over time,” Professor Syndercombe Court explains. “So we determine how much methylation is on a bit of DNA. And we use markers, areas of the DNA that we know are susceptible to methylation or demethylation, as people get older.”
“There's other intelligence that we can get out of DNA today, but it's not great. Things like eye color, hair color, skin color. But the accuracy is not wonderful,” she adds.
Mitochondrial DNA Testing
Another type of DNA called mitochondrial DNA is found outside the cell nucleus, inside the energy-generating mitochondria. So how is mitochondrial DNA used in forensic science?
In the case where regular DNA is very degraded, mitochondrial DNA extraction and analysis can help with identification – in fact, mitochondrial DNA was used to identify the remains of Britain's King Richard III a staggering 527 years after he died.
“The ability to look at the mitochondrial DNA has improved considerably over the last five years or so, partly because of the work done by people looking at ancient DNA. They've developed good methods for looking at things like Neanderthals and these very, very ancient skeletons. And forensic geneticists are beginning to use those same techniques where the DNA is very, very degraded or contaminated,” Professor Syndercombe Court says.
“The good thing about mitochondrial DNA is that there's lots of it,” she explains. “The bad thing about it is that it doesn't define the person – it's inherited down the maternal line. So it will be identical in all maternally related individuals, but it can help give some sort of inference about where that person might have come from geographically in the world.”
Also called Ridgeology, analyzing the ridges and whirls on a person’s digits can be a pretty good indicator of who a person is. However, like many other identification methods, it relies on good antemortem records, or records made before death.
“If you’ve got good fingerprints left on the body then you can use those, but again they’ve got to be on a database,” Professor Syndercombe Court says.
According to the College of Policing’s Authorised Professional Practice, multiple avenues to obtaining antemortem fingerprint records exist. These include “fingerprints taken by the police and held by the Criminal Records Office, fingerprint records in biometric passports or on digital devices, workplace biometric data, which may include fingerprint records held by the human resources or personnel department.”
How are dental records used to identify a person?
Identifying remains via dental records is called Forensic Odontology. Interpol’s page on disaster victim identification states that “Teeth provide one of the most reliable forms of identification as they are highly durable and most people have dental records.”
The structure and arrangement of every person's teeth are different, so matching up antemortem dental records and postmortem scans can give very useful identification information. Examining dentures and dental work such as fillings can also help.
“The teeth are the hardest tissue in the human body and are the most resistant to trauma, decomposition, water immersion and fire,” the College of Policing’s website states, explaining that dental records can be used for identification for dead bodies that are very damaged or decomposed.
“Above a certain age, your teeth don't change very much except they fall out,” notes Professor Syndercombe Court.
The first person to be identified using their teeth was Joseph Warren, who died during the Battle of Bunker Hill in 1775 at the start of the American War of Independence. His remains were badly mutilated, so dentist Paul Revere identified him in 1776 by recognizing a prosthetic tooth he had given to Warren.
Dead body identification via medical implants
“If you've got a registration number on some sort of anatomical bit of metal, then you can be pretty sure that it's that person because that surgeon put it into that person,” Professor Syndercombe Court states.
One person who was identified via implants was Jasmine Fiore, a model whose husband was charged with her murder. Jasmine’s body was found with removed teeth and fingertips, eliminating the ability to identify her via dental records or fingerprints. However, authorities were able to use the serial numbers on her breast implants to reveal her identity.
Implant serial numbers can be used to identify the surgeon who implanted them, the date of implantation, and most importantly the recipient of the implant. Laws in many countries mean that medical implants must have serial or lot numbers for quality control purposes, for example in the case of recalls.
A 2013 case report in the journal Medicine, Science and the Law describes the case of a woman's body found floating in a river in Japan. Radiographs of the body showed that she had an intramedullary nail implanted in her femur.
The nail was made of multiple parts, each with its own lot number. Police contacted their manufacturing company, which gave over the use history for the nail parts. This revealed the hospital where they were used and the date of the implant surgery, allowing police to confirm the patient's name with the hospital and identify the body.
Visual identification of dead bodies
A person’s appearance is generally a good indicator of their identity – but it can’t always be relied on, especially if their body is not in pristine condition – for example, victims of major disasters such as terrorist attacks or earthquakes.
According to the College of Policing, visual identification alone is not a reliable form of identification and should be used for assistance only.
“I've seen anecdotes, when somebody is dead, they may look very different. The muscles may be in a more lax condition. It just depends on how well preserved a body is,” says Professor Syndercombe Court.
However, certain parts of a person’s appearance can be a telltale sign of who they are – distinctive tattoos, birthmarks, and scars are good examples.
For example, in 1935, a recently-caught tiger shark at Coogee Aquarium in Sydney vomited up a human arm. The limb had a tattoo of two boxers sparring, and this alongside fingerprints showed that the arm was that of a man called James "Jimmy" Smith.
How are decomposed bodies or skeletal remains Identified?
“If you've just got a bone or a skull, certainly bits of the skull can give you good bits of DNA,” explains Professor Syndercombe Court. However; “If the body's been left in a burial site for a long period of time it can get contamination.”
“So in the ear, there are bones that haven't been exposed to the environment at all, so that DNA is much better preserved. This bone, called the petrous bone, we quite often go for,” she adds. “If you go for something like a petrous bone, nobody will have touched it. You have to break open that bit of the skull in order to access that bit of bone.”
Computed Tomography (CT) scans of bodies can also be useful for identification, allowing comparison of anatomical features.
One case report describes a “highly decomposed human body, aged between 30 and 40 years,” found in a Brazilian forest in 2013. The police suspected that the body was that of a woman who had been missing for seven days at this point. After the missing woman’s family provided CT scans of her head, she was positively identified due to the appearance of her sinuses being consistent in both antemortem and postmortem scans.
Forensic facial reconstruction can also help identify skeletal or decomposed remains, however this only provides an approximation of what the deceased’s face may have looked like. It is often a last resort, but has seen some success.
Remains can be radiocarbon dated to estimate when the person died and when they were born. In 1983, human remains were found in a peat bog in England. Believing the remains to be those of his wife, a local man confessed to her murder. However, carbon dating revealed that the body was actually 1,600 years old, remaining well preserved in the conditions of the peat bog.
How many unidentified bodies are there?
As of December 2021, 13,885 unidentified persons cases in the US remain unresolved according to the National Missing and Unidentified Persons System. These cases have been ongoing for an average of 22.4 years, with 54 percent unresolved after 20 years.
The UK Missing Persons Unit states that they record around 120 unidentified people per year, with their database containing 1,200 open cases.
A 2018 study in the journal Forensic Science International stated that over 20,000 migrants died in the Mediterranean in the past 10 years, with over 60 percent remaining unidentified due to data recovery difficulties.
With modern tools, we can even identify the remains of people who died thousands of years ago. As forensic science continues to advance, hopefully these unidentified people can be identified, bringing closure to their loved ones.