现代科学技术手段有助于破案

Scientists have developed a technique to estimate the age of a suspect from blood left at a crime scene.

Experts say the profiling method could be put to immediate use by forensic scientists where age information can provide investigative leads.

The technique exploits a characteristic of immune cells carried in the blood known as T cells.

The work by a team in the Netherlands has been published in the journal Current Biology.

T cells play a key role in recognising foreign "invaders" such as bacteria, viruses, parasites, or tumour cells.

As part of the process these cells use to recognise these invaders, small circular DNA molecules are produced.

The number of these circular DNA molecules - known as signal joint TCR excision circles (sjTRECs) - declines at a constant rate with age.

Writing in Current Biology, the researchers said they had shown that this biological phenomenon could be used for estimating the age of a human individual "accurately and reliably".

Unknown persons

The approach enables scientists to estimate a person's age, give or take nine years, the researchers report.

This would allow individuals to be placed into generational categories spanning about 20 years.