A paid police informant in Jimmy Melvin Jr.'s first-degree murder trial told a Halifax jury Monday that he knew about Melvin's plan to kill Terry Marriott Jr. when he drove him to a Harrietsfield home where the victim was sleeping.

Derek MacPhee drove Melvin through the woods on a four-wheeler to the home of his friend, John Lively, at around suppertime on Feb. 20, 2009.

"I heard bang, bang and then there were slow bangs — bang, bang, bang, I couldn't believe how loud it was," Derek MacPhee, the Crown's star witness, testified on the first day of Melvin's trial at Nova Scotia Supreme Court in Halifax.

Loaded guns

Melvin is charged with first-degree murder in the shooting death of Marriott. Both MacPhee and Melvin went to the scene armed with loaded guns.

Jimmy Melvin is on trial for first-degree murder. (YouTube)

"I grabbed a .38 and put it in my pants in case something went wrong, in case I had to go in and save Jimmy," MacPhee testified. He said Melvin carried a .357 gun.

MacPhee, a career criminal who told the court he sold drugs and has stolen more than 300 cars, testified he and Marriott smoked cocaine daily, and also took pills and drank on top of that.

MacPhee also admitted he has given information to police at least 40 times.

Witness friends with Melvin and Marriott

Terry Marriott Jr. was killed on Feb. 20, 2009. (Facebook)

In her opening address, Crown attorney Christine Driscoll said only two people know exactly what happened the day Marriott was shot to death — Melvin and MacPhee.

MacPhee was good friends with both men. He said he'd once tried to reconcile Marriott and Melvin over a dispute they'd had with each other. He thought things were fine between the two men before the shooting.

Court heard that in the early morning of Feb. 20, 2009, Marriott was beaten badly at Ralph's strip bar in Dartmouth in an unrelated matter. He went to Lively's house later that morning to sleep off the partying.

Lively gave Marriott his daughter's blanket, which had Disney princesses on it.

"Mr. Marriott never got off that couch," Driscoll said. "Instead, around suppertime, he was discovered there by Derek MacPhee, a friend of his. Mr. Marriott had been shot several times in the head and the body. He was dead."

'I didn't want him to be killed'

MacPhee told the court that he and Marriott sold an ounce or two of drugs every week, bringing in $1,000 profit.

On the day of the homicide, MacPhee said he smoked crack and took Valium and when Marriott showed up at his house looking for cocaine he gave him 14 grams and some sleeping pills.

When Melvin showed up at MacPhee's house that morning, he was high and "acting crazy," MacPhee recalled.

"He's talking about killing Terry in my house," MacPhee said, adding he opposed that plan. "I didn't want him to be killed, period."

5-week trial

The Crown alleges that Melvin, armed with a loaded handgun, went into the TV room in the basement of Lively's home where "Mr. Marriott was sleeping completely defenceless and shot Mr. Marriott to death before fleeing."

MacPhee woke Lively, who was in a room nearby, and they called 911, Driscoll said.

MacPhee drove Melvin from the scene. MacPhee agreed to testify against Melvin in exchange for an immunity deal, which includes wiping out charges he faced in a violent home invasion in Upper Sackville.

He is in witness protection.

The trial is set for five weeks.