NEWMARKET, Ont. -- A drunk driver who killed three children and their grandfather in a horrific crash told the grieving family Wednesday that he wished he could erase his "inexcusable" actions, but his apology was rejected by the children's parents.

Marco Muzzo, 29, faced a packed courtroom as he expressed the sorrow and regret he said have been consuming him since the Sept. 27 tragedy in Vaughan, Ont.

"I am tortured by the grief and the pain that I have caused the entire family," he said. "I will forever be haunted by the reality of what I have done. I am truly sorry."

His voice trembling at times, Muzzo acknowledged that his words could bring no consolation to those whose lives have been irreparably harmed by his behaviour.

But he vowed to work to make amends by educating others on the dangers of drunk driving.

"I will spend the rest of my life attempting to atone for my conduct," he said.

Muzzo pleaded guilty earlier this month to four counts of impaired driving causing death and two of impaired driving causing bodily harm.

Nine-year-old Daniel Neville-Lake, his five-year-old brother Harrison, their two-year-old sister Milly, and the children's 65-year-old grandfather, Gary Neville, died after the van they were in was hit by an SUV.

Jennifer and Edward Neville-Lake, whose family was decimated in the crash, left the room as Muzzo took the stand and did not return until he was back in the prisoner's box.

Outside court, Jennifer Neville-Lake said the couple had no interest in what Muzzo had to say and questioned the sincerity of his remorse.

In the end, she said, whether or not Muzzo is sorry is "irrelevant," since nothing can bring back their loved ones, she said.

The family has even requested a court order barring Muzzo from contacting them from behind bars, though his lawyer said Muzzo would respect their wishes without an official restraint.

Just a day earlier, Neville-Lake had stared down Muzzo as she delivered an emotional statement to the court, saying his actions had shattered her world and robbed her of her identity as a mother.

It's common for mourning families to dismiss the apologies offered by drunk drivers, said Andrew Murie, CEO of Mothers Against Drunk Driving Canada. And while offenders often vow to change, few fulfil their promises, he said.

Muzzo's lawyer, Brian Greenspan, said his client is "grief-stricken" and takes full responsibility for his actions.

The crash was the result of a "terrible decision made by a very good person" who had otherwise led a "virtually exemplary" life, he said.

The Muzzo family, one of Canada's wealthiest, owns the drywall company Marel Contractors and is worth nearly $1.8 billion, according to Canadian Business magazine.

Dozens of people, including relatives and employees of the family business, wrote letters denouncing what they called an unfair portrayal of Muzzo in the media.

A neighbour said Muzzo, who he has known for years, was always willing to lend a hand, while an employee described him as "humble beyond words and loved by everyone."

His fiancee said the pair were inseparable and had spent the last few years building their home. They were set to be married in October, but those plans were derailed after Muzzo's arrest.

A compassionate and helpful man, Muzzo took over caring for his family after losing his father to cancer a decade ago, Taryn Hampton said in her letter.

The Crown, meanwhile, compared Muzzo's actions to walking down the street with a loaded gun.

"It is time to send a message," Crown lawyer Paul Tait said in calling for a sentence of 10 to 12 years and a ban on driving for eight to 10.

"Every drunk driver makes a choice and in this case that choice resulted in catastrophic consequences for the victims' family," he said. "An entire generation of the Neville-Lake family was wiped out in one fell swoop."

There is no maximum sentence for impaired driving causing death and Tait said the judge could impose a sentence beyond what he requested, noting that it would set a strong precedent.

The defence has argued an eight-year sentence would be sufficient, with credit for the four months he has already spent in custody.

A psychiatric report filed with the court Wednesday said Muzzo is showing signs of post-traumatic stress disorder and mild depression.

Dr. Graham Glancy, who conducted the evaluation, said Muzzo shows "considerable remorse" and appears "distressed and tearful" at times, particularly when discussing the crash.

The psychiatrist said Muzzo told him he was stunned by the breathalyzer results, which court has heard were between two and three times the legal limit.

He said Muzzo recalled drinking until 3 a.m. the night before the crash but feeling fine in the morning. Muzzo remembered having three to four drinks on a plane before taking the wheel, but did not feel drunk.

Court has heard he was returning from his bachelor party in Florida on a private plane and picked up his car at Pearson International Airport.

Muzzo is to be sentenced on March 29.