An increasing number of them committed their crimes many years ago but have been caught by advances in DNA techniques.

"I have been studying re- growth and DNA techniques," she said.

In the end, the researchers found 31 new species of bacteria with the DNA technique and just 6 from laboratory cultivation.

Scientists took samples from the trees and used DNA techniques to identify them as new species.

The DNA technique has already been used to spectacular effect, even trapping a murderer.

The three were arrested yesterday after police used new DNA techniques to examine evidence obtained at the time of the murder.

The medical examiner's office intends to continue trying to identify the dead through at least early next year, relying on advanced DNA techniques.

And there are outright dangers, like the possibility that DNA techniques will be used to make novel biological weapons.

The tests would be the first of a pesticide formed by modern recombinant DNA techniques.

Some of the dead remain unidentified to this day, even with modern DNA techniques.