LONGUEUIL, Que. - The Crown says it has little doubt who pulled the trigger when a Laval police officer was shot three times inside a sleepy residence in the wee hours of a snowy March morning more than a year ago.

But Basil Parasiris, the man accused of the crime, seemed relaxed and calm as his first-degree murder trial opened Wednesday.

Parasiris, 42, has pleaded not guilty to four charges including first-degree murder in the killing of Laval police Const. Daniel Tessier and the attempted murder of his partner, Const. Stephane Forbes.

On Day 1 of Parasiris' jury trial, Crown prosecutor Joelle St-Germain said evidence would show Parasiris was the one who pulled the trigger first after police rammed open the door of his house.

Tessier was struck three times as a firefight broke out inside the accused man's suburban home.

"The Crown's case is not a whodunit,'' St-Germain told the jury in her opening statement at the Longueuil courthouse on Wednesday.

"Basil Parasiris is the one who shot Daniel Tessier and Stephane Forbes.''

A six-man, six-woman bilingual jury started hearing testimony on Wednesday after receiving directions from Quebec Superior Court Justice Guy Cournoyer.

Tessier, 42, was a 17-year veteran of the Laval police and the father of two girls.

Tessier's wife and some of his colleagues from the Laval force lined the first row of seats in the courtroom on Wednesday as St-Germain gave the jury a brief overview of the Crown's case.

"Evidence is like a puzzle,'' St-Germain said. "At the end the case, all pieces have to fit in place so a verdict can be rendered.''

The defence will present their own case once the Crown is done.

St-Germain said Laval police officers travelled to nearby Brossard early on March 2, 2007.

It was just after 5 a.m. when nine Laval officers knocked in the door and made their way into the Parasiris home.

Within 30 seconds Tessier, Forbes and three other officers scurried upstairs while the remaining officers secured the ground floor.

The prosecutor said Parasiris opened fire, shooting Tessier three times. A fourth shot hit Forbes in the left arm.

"The evidence will show that Tessier had no chance to get out of the way,'' St-Germain said.

Officers shot back, firing 14 times. One shot hit Parasiris' wife in the arm.

But police did not fire a single shot until Parasiris opened fire first, St-Germain said.

Police would later find a Ruger .357-Magnum in Parasiris' bedroom, in addition to three other loaded weapons in the house.

St-Germain says she plans to call some 30 witnesses, including a pathologist and experts in ballistics and blood spatter patterns.

The trial began with four crime scene experts from the Quebec provincial police describing what they found inside the Parasiris home. Hundreds of photographs were entered into evidence.

Tessier's widow, Dominique Lapointe, was overcome as photographs of her late husband's body, covered on a hospital gurney, were flashed on a projector screen for the jury.

All of Tessier's colleagues inside the house at the time of his death will also testify, St-Germain said.

In addition to crime scene technicians and detectives, a recording of a pair of 911 calls placed from the Parasiris home will also play a part in the Crown's case.

Parasiris has been free on bail since April 2007.

It is believed to be the first time a judge in Canada has granted bail to an alleged cop killer.

The trial is expected to last four to six weeks.