DNA discovered on shell casings at a murder scene was likely linked to alleged gunman Julian Washington, a forensic officer told the Supreme Court yesterday.

While the expert told the court the DNA recovered from the casings was of “low quality” and she could not determine a major donor, she testified that testing revealed a partial match with the defendant.

Mr Washington, 24, has denied the premeditated murder of 24-year-old Stefan Burgess and the attempted murder of Davano Bremer, along with charges of using a firearm and handling ammunition.

The court heard earlier this week that both victims were attending a birthday party on the evening of January 8, 2012, when a man wearing a dark helmet and clothing opened fire.

The gunman then fled the scene, riding away on a waiting motorcycle.

Mr Bremer suffered a non-fatal gunshot wound to his groin but Mr Burgess was shot twice in the upper body and was later pronounced dead on arrival at King Edward VII Memorial Hospital. Mr Washington was arrested in connection with the shooting the following day.

Prosecutors alleged that days before the shooting Mr Burgess had fought a friend of the defendant, Anthony Smith, knocking out one of his teeth.

As the trial continued yesterday forensic scientist Candy Zuleger told the court how she swabbed several firearm cartridges recovered from the scene for DNA, comparing the results from DNA samples from Mr Washington, Mr Bremer, Mr Smith and one other.

She said she combined the DNA samples from all of the cartridges into a single composite sample, explaining that little DNA could be recovered from the individual cartridges.

The tests revealed a DNA mixture with several donors, but she was unable to determine a major or minor donor.

While the results excluded Mr Bremer, Mr Smith and the other suspect, there was a partial match with Mr Washington.

She estimated the odds of the DNA coming from another donor in the black population of Bermuda at one in 46 million, or one in 173 million in the white Bermuda population.

Ms Zuleger also told the court that she tested the neck and hood of a black jacket, which had been seized by police.

In that case they was able to detect three donors, with Mr Washington being identified as the major donor.

She explained that the odds of a person in the black Bermuda population other than Mr Washington being the major DNA donor on the jacket was estimated at one in two sextillion — a figure with 21 zeros.

However, she also agreed that she could not say for certain how or when the DNA came to be on the items.

Under cross examination by defence lawyer Larry Mussenden, Ms Zuleger agreed that the sample of DNA collected from the cartridges was “low quality”, saying: “There was very little DNA on the swab in this case. That’s why we do a composite swab.”

She said the tests indicated “at least” three donors and reiterated that she could not determine when a donor’s DNA came in contact with an item, noting that DNA can remain on an item for years if kept in a cool, dry environment.

And she agreed that the testing could not confirm if Mr Washington himself had loaded the cartridges into a firearm or discharged that firearm. The trial is set to continue in the Supreme Court on Monday.