The Halifax jury that acquitted Jimmy Melvin Jr. on Friday of murder was not told during his trial that he's spent part of his adult life behind bars, or that he is also charged with trying to kill rival Terry Marriott Jr. only a couple of months before the victim's death.

Melvin chose not to testify in his own defence in Nova Scotia Supreme Court, which means he was never questioned in court about his criminal past and it was not revealed to the jury.

Parole Board of Canada records from over the years detail that past and his violence while in prison. They also say Melvin has sought criminal notoriety and was diagnosed with anti-social personality disorder.

Melvin had been on trial over the last four weeks for first-degree murder in the death of Marriott. Marriott was shot multiple times while he napped at a friend's Harrietsfield, N.S., home on Feb. 20, 2009.

The jury was sequestered Thursday night and continued deliberations Friday. It came back with its not guilty verdict on Friday afternoon.

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Terry Marriott Jr. (Facebook)

'Highly criminalized family environment'

Even so, Melvin remains in custody. He is scheduled to return to court on Sept. 11 on a charge of attempting to murder Marriott, related to a Dec. 2, 2008, incident. His co-accused in the case is Regan Henneberry, whose trial is set to begin Oct. 30.

Melvin's criminal record dates back at least 17 years. He is from a "highly criminalized family environment" and his criminal values seem deeply rooted, according to one parole board decision.

In 2000, he kicked, punched and struck another person with a pool cue. During the assault, the victim lost consciousness and required stitches, his parole board documents show.

Melvin's first federal sentence

In 2001 at age 22, Melvin began serving his first federal prison sentence for conspiracy, assault causing bodily harm and drug trafficking. He had also violated a court order by possessing a box of .22 calibre ammunition.

While on remand, Melvin told officers he always had a weapon on him when he was on the street, according to 2006 parole board documents. 

"You also used [a] baseball bat, hockey sticks and pepper spray in the past," the decision said.

The parole board noted that Melvin demonstrated violence and intimidation from the start of his criminal career.

Comfortable with criminal lifestyle

"You have demonstrated that you are very comfortable with your criminal lifestyle," the decision said. "You have expressed a desire to establish notoriety among the criminal element, naming individuals well known in the criminal justice system as idols."

Inside prison, Melvin often intimidated guards, threatened them and threw urine at them. He was also involved in fights with other inmates, the documents said.

"Furthermore, you threatened to harm staff members directly, or their families," the parole board said. "Your threats were very explicit and very violent."

In 2004, Melvin was involved in a serious fight inside prison where he used a hockey stick to assault three people. The three victims were treated in hospital for head injuries.

The same year, he was diagnosed with antisocial personality disorder with narcissistic traits and possible substance abuse disorder.

A 2005 parole board decision identified Melvin as one of the leaders of a gang involved in drug trafficking in prison. Two prior security reports in 2005 said Melvin had issued a contract to kill another offender.

"This is linked to your involvement in the drug subculture," the board wrote.

'Will be 40 times worse'

During one review for parole, Melvin told the panel he was a heroin addict and "when I get out, I will be 40 times worse."

"You acknowledge that your behaviour is not normal but you do not know any other alternatives," the board wrote at the time.

It ordered Melvin to remain in prison until his sentence ended. Melvin was released in May 2006 after serving five years.

Melvin himself has been a victim of a shooting in the past. He was shot in the abdomen in Halifax's Cowie Hill neighbourhood on Dec. 4, 2008. He suffered non-life-threatening injuries. In 2010, Jeremy Alvin LeBlanc was sentenced to 16 years in prison for the shooting.

MacPhee's involvement in Marriott's murder

Derek MacPhee takes a drink in this photo posted to Facebook.

Derek MacPhee, seen in this photo posted to Facebook, testified at Jimmy Melvin Jr.'s trial. (Facebook)

In Melvin's first-degree murder trial, the Crown based much of its case on the testimony of paid police informant Derek Thomas MacPhee.

MacPhee, 36, told the court he drove Melvin on a four-wheeler to and from the murder scene where Marriott was sleeping off a night of partying. Melvin, he said, had a .357 gun, while MacPhee brought a .38 gun.

In June 2015, MacPhee and two other men were arrested and charged in June after a violent home invasion in Upper Sackville.

RCMP said at the time that two men broke into the home and tied up a man, his wife and their 13-year-old child. The robbers fled with stolen items.

Charges against MacPhee in that case and Marriott's murder were dropped in exchange for his testimony against Melvin.

MacPhee began working as an informant in May 2004. He is a career criminal who has stolen more than 300 cars and lied in the past to police and the courts. He is now in witness protection.

Court also heard that after Marriott's murder, MacPhee shot his friend, Regan Henneberry, in the leg four times in May 2009 because Henneberry broke MacPhee's nose in an earlier fight.