The jury at the attempted murder trial of Ronald Wasser heard from two firearms experts on Thursday.

​Wasser, 48, of Riverview, is accused of trying to kill his estranged wife with a shotgun on May 29 — the day after what would have been the couple's 25th wedding anniversary.

Moncton court

The jury at Ronald Wasser's attempted murder trial heard from a firearms specialist on Thursday. (CBC)

Norma Wasser, 49, suffered a severe wound to her left arm, the Moncton Court of Queen's Bench heard earlier this week. The shot broke her left arm in two places and broke an artery.

Terry Pipes, a firearms specialist with the RCMP forensic lab in Halifax, tested a 12 -gauge shotgun that was seized from the Wassers' home on Kerry Court on the morning in question.

He also looked at the expended shell found at the scene and concluded it was fired from the seized shotgun, he testified.

Police found an unused shotgun shell in Ronald Wasser's pants' pocket. Pipes said it was a 12-gauge shell and could be used in the seized shotgun.

No gunshot residue on accused

No gunshot residue was found on four swabs taken from Wasser's hands and face, Nigel Hearns, a gunshot residue expert from the national RCMP forensics lab in Ottawa, testified.

Gunshot residue can be washed or wiped away, he said.

Up to 90 per cent of residue is lost within the first two hours of a weapon being fired, he added. The samples from Wasser were taken within four hours of the shooting, the courtroom heard.

Several other factors are involved in gunshot residue, including the firearm itself, the mechanism, how it's loaded and how the bullet is ejected, said Hearns.

A pistol, for example, produces a lot of residue, while a single barrel shotgun, like the one in question, won't produce as much, unless it's opened, he said. Residue would be found on whoever opens the gun, Hearns said.

Earlier in the trial, RCMP Const. Sebastian Houle testified he grabbed the shotgun from Wasser's bed for officer safety and checked it to see if it was still loaded, which involves opening the gun. There was still a shell in the barrel, the officer said.

Pills found at bedside 'major tranquilizer'

The jury also heard from a toxicologist from the national forensic RCMP forensics lab in Ottawa. Christopher Keddy talked about the effects of Seroquel.

Paramedic Jeff Smith previously testified he found bottles of pills on Wasser's bedroom dresser that morning and that Wasser was unresponsive. Some of the bottles were open and a bottle of Seroquel was empty, Smith said.

Seroquel is used to treat schizophrenia and bipolar disorder, said Keddy. He called it a "major tranquilizer" and taking too much could affect a person's central nervous system, and could cause death, he said.

Keddy could not say when the drug was ingested.

Wasser is also charged with discharging a firearm at Norma Wasser with the intent to wound or endanger her life, assault with a weapon, assault causing bodily harm, aggravated assault, and possession of a weapon for a dangerous purpose.

The trial was late getting started on Thursday, partly due to the winter storm as well as some preliminary discussions between the judge and lawyers, which can't be reported because the jury was not present.

The Crown is expected to wrap up its case on Friday.

The trial, which started on Monday, is expected to take four weeks.