CHARLOTTETOWN -- A Prince Edward Island man killed a father and son to avenge the death of his sister in 1970, court heard Monday as he was ordered to serve 35 years in prison before he can apply for parole.

Alfred Guy Vuozzo was given an automatic life sentence after pleading guilty to first- and second-degree murder in the shooting deaths of Brent McGuigan, 68, and his son Brendon McGuigan, 39.

At Vuozzo's sentencing hearing in provincial Supreme Court in Charlottetown, Crown lawyer John Diamond read an agreed statement of facts describing the motive behind the fatal shootings near Montague last summer.

Diamond said Brent McGuigan's father was the driver of a vehicle involved in a collision that killed Vuozzo's nine-year-old sister 45 years ago.

The execution-style slayings last year of Brent and Brendon McGuigan were among the worst in the province's history, Diamond said, adding that Vuozzo murdered the men knowing that they had no direct connection to the accident other than being related to the driver.

Vuozzo, 46, has suffered from depression for years and on Aug. 20 he went to the McGuigan household where he shot the men multiple times with a handgun to seek retribution for his sister's death, Diamond said.

"It was revenge," Diamond told the court. "He was a cold-hearted and calculated individual."

Before he was sentenced, Vuozzo addressed the court. He said he has been tormented since Brent McGuigan's father received a nine-month sentence for the crash that killed his sister.

"That's all her life was worth," said Vuozzo, who was two years old at the time of the crash. "She only had nine years in this world. And nobody cared.

"It's haunted me all my life."

The provincial court in Charlottetown could not confirm Monday that Brent McGuigan's father was sentenced to nine months in prison for the accident.

More than a dozen victim impact statements were submitted with the court. In one of them, Brent McGuigan's only daughter Donna said she has become consumed with hatred as a result of the killings.

"I feel so much anger and hatred that it scares me," she told the court, sobbing. "I hate that they died this way and it haunts me."

Marie McGuigan, Brent's widow and Brendon's mother, said her life has changed forever.

"I pray to God everyday for strength," said Marie, who was home at the time of the murders and discovered the gruesome scene.

"I will never be the same. ... A part of me died with them that night."

There were several emotional outbursts in the courtroom, including one that led to a man being ejected from the public gallery.

After the sentencing decision was read, Vuozzo cursed and screamed, resisting the officers as he was taken from the courtroom while members of the public cried and yelled back at him.

Diamond had argued Vuozzo should be ineligible for parole for 50 years, while the defence sought 25 years before he could apply for parole.

Judge Gordon Campbell said a parole ineligibility period of 50 years would be unduly long.

"Such a sentence would go beyond retribution and become vengeful, and that would not be just," said Campbell.

But Campbell said the defence's sentencing request would also not have been fair because it would have failed to acknowledge the loss of two lives.

Federal legislation passed in 2011 allows courts to impose consecutive periods of parole ineligibility for people convicted of multiple murders.

Vuozzo was given 25 years of parole ineligibility for the first-degree murder charge and another 10 years for the second-degree murder charge.