Scientists in the US are working on a new way to identify someone when there's not enough of that someone around to easily figure out who they are.
All it would take is a little hair.
So far, the researchers have found a total of 185 hair protein markers, which could distinguish a person from a group of one million.
They're looking for a specific, core set of 100 protein markers that could distinguish a person from the entire world's population using just a single hair.
That would be a big help to crime scene investigators and archaeologists and could one day end up dethroning the current go-to: DNA testing.
That's because DNA is susceptible to environmental and chemical processes and can degrade over time - protein is more stable.
In fact to prove that, in their lab, the researchers even used samples that were 250 years old.
DNA testing has been around since the 80s.
Before that, fingerprinting was used in the early 1900s and considered the best way to find out "whodunnit".
Before that police prosecution often relied on witness evidence.
Otherwise, torture was sometimes used to elicit a confession, known as "third degree" interrogation - which is where we get the expression.
Hair strand analysis will likely prove to be far more reliable.