19 April 2012 Last updated at 11:12 ET

The DNA of murder accused Ross Monaghan was found on one of the guns used to shoot gangland figure Kevin 'Gerbil' Carroll to death, his trial has heard.

Forensic scientist Pauline McSorley told jurors the chance of the DNA belonging to anyone other than Mr Monaghan was one in a billion.

But the High Court in Glasgow heard the DNA of a laboratory technician was also found on the weapon.

Mr Monaghan denies murdering Mr Carroll in an Asda car park in January 2010.

The court heard that the gun - a black self-loading pistol - was found alongside a revolver behind Coatbridge Library on 26 January 2010.

Mr Carroll, 29, had been shot dead 13 days earlier at an Asda car park in the Robroyston area of Glasgow.

Giving evidence to the trial, Ms McSorley told advocate depute Iain McSporran, prosecuting, that the gun was swabbed and they found DNA from "at least three people."

It's horrendous that should have happened from a scientific point of view

She said the major source of the DNA was 30-year-old Mr Monaghan, and described it as a "perfect match".

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'DNA of Gerbil accused' on pistol