Prints left by the hand, or even parts of it, can be used to estimate the height of an unknown intruder and possibly tell whether they were male or female, say researchers.
A team led by forensic anthropologist Associate Professor Daniel Franklin, from the University of Western Australia, report their findings in a series of recent scientific papers.
"That might be useful if you've got someone who has broken into a house or someone has been seen messing around with a window of a house," says Franklin.
When trying to identify a suspected perpetrator of crime experts try to narrow down the list of potential suspects.
Eyewitness accounts are notoriously unreliable. But Franklin and colleagues, including Nur-Intaniah Ishak from the University of Malaya, in Malaysia, have been investigating the use of handprints to predict the likely stature and sex of a perpetrator, which they report in a paper published in the journal Forensic Science International.
The researchers took measurements of 91 male and 100 female adults from Western Australia. They measured the height of each individual and took seven measurements of each hand and its corresponding print.
Franklin and colleagues measured hand breadth and length, palm length, as well as the length of the first, second, third and fourth digits.
They then carried out a statistical analysis and found that handprints involving these parts of the hand could be used to estimate height.
"If you're taller you tend to have longer limbs and you tend to have bigger hands as well. It's a scaling effect," says Franklin.
"We can show that there is a strong correlation between the size of your hand and your ... height and the same thing applies to a print from a hand."
Narrowing down suspect list
Franklin says a forensic investigator could use these statistics to get a quantifiable estimate of an offender's height and this would help narrow down suspect profiles given out to the public or could be used to narrow down a given list of suspects.
Franklin says the study showed handprints can predict height with a relatively high degree of accuracy, close to that of height predictions from hand bones.
"The degree of error is close to as good as we can get," he says.
"This is a surprising degree of accuracy and needs to be tested in a larger population."
Franklin says human biological variation means it is impossible for the prediction to be 100 per cent accurate.
But, he adds, it's good enough for narrowing down a potential pool of candidates, who can then have their fingerprints or DNA taken.
"You're not convicting people and it's not going to give you a positive ID but it helps," says Franklin.
"It's an added bonus where there is a handprint at a crime scene."
In a related unpublished paper, Franklin and colleagues used the same handprint size data to predict sex.
"We're not saying that every male is bigger than every female but, on average, in the sample, males were significantly larger than females in terms of their hand dimensions," says Franklin.
The team is also involved in building up a database that will enable forensic investigators to establish the sex, height or age of a victim of crime based on the size of different bones in their skeletal remains.
This can be used to narrow down possible victim identities from a pool of missing persons, for example, before using DNA tests and dental records, which would ultimately used for a positive identification.
"You don't want to be looking at 1000 dental records to match one unknown," says Franklin.
Currently, he says, Australian experts rely on a database containing largely overseas data, which may be, for example, from people in the United States collected two decades ago.
"They're going to be very different people to what we have in Australia at this given time," says Franklin.