The Supreme Court heard yesterday that particles associated with gunshot residue (GSR) were discovered on the clothing of accused gunman Julian Washington.

However, defence lawyer Larry Mussenden suggested that the particles identified by experts could have come from fishing equipment, noting that no true GSR was found.

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 last week that on the evening of January 8, 2012, both victims were attending a birthday party when a man wearing a dark helmet and clothing entered and 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 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, the court heard evidence from forensic scientist Alison Murtha, who said she tested a series of swabs from items seized during the investigation for gunshot residue (GSR).

She explained that when a firearm is discharged, antimony, barium and lead are all released in a plume, spreading up to around five feet from the weapon. When all three elements fuse together, it forms GSR. While true GSR containing all three components is only formed by shooting a firearm, particles made up of one or two components can come from either firearms or sources such as fireworks and brake pad linings.

Once particles are identified, she said they are examined to see if they had been treated by heat and pressure, which would indicate that they had been discharged from a firearm. Any particles which do not match that appearance are dismissed and not counted as they could come from another source.

Ms Murtha said that none of the swabs she tested in connection to this trial were found to contain three component GSR, however two-component particles made up of lead and antimony were discovered on Mr Washington’s left boot and on a black jacket.

Almost all of the items swabbed, including the clothing Mr Washington was wearing when he was arrested, were found to have individual lead and antimony particles on them, but only the black jacket, his right boot and his helmet were found to have any particles of barium.

Ms Murtha told the court that the lack of three-component particles did not mean the particles found were not caused by a firearm, saying: “If there were three component particles present, it would only make a stronger association.”

Under cross examination by Mr Mussenden, Ms Murtha agreed that lead and antimony can be found in fishing equipment, specifically sinkers, and in weights used in scuba diving.

She also agreed it was possible someone who had been in contact with solid fishing sinkers, or had been melting metals in a pot, could be exposed to lead and antimony, but barium particles would have to come from a different source.

But re-examined by prosecutor Garrett Byrne, Ms Murtha said the lead-antimony particles in fishing weights usually contain only trace amounts of antimony — unlike those found on Mr Washington’s clothing — and typically do not appear heat treated.

The trial is expected to continue today.