An unexpected twist in the biggest mass murder trial in Canadian history: just six weeks before the Air India trial was set to begin, one of the accused, Inderjit Singh Reyat, has pleaded guilty to one charge of manslaughter.

He has been sentenced to an additional five years in prison.

All other charges against Reyat including first-degree murder and conspiracy to commit murder are being stayed.

Inderjit Singh Reyat during court proceedings at B.C. Supreme Court in Vancouver Monday (CP PHOTO)
Inderjit Singh Reyat during court proceedings at B.C. Supreme Court in Vancouver Monday (CP PHOTO)

Reyat was charged along with Ripudaman Singh Malik and Ajaib Singh Bagri with conspiracy and murder. In 1985, a bomb ripped through Air India flight 182 as it flew near the coast of Ireland, and killed all 329 people on board, most of them Canadian.

Reyat, 51, sat quietly on Monday morning, behind the bulletproof glass the province installed as part of the high security courtroom for the Air India trial.

Dressed in a dark blue turban and beige corduroy jacket, he stood quietly as the court clerk read the new charge against him.

Geoff Gaul, the spokesperson for the prosecution service, described what happened then.

"Inderjit Singh Reyat pleaded guilty to one count of manslaughter in relation to his role in the explosion and crash of Air India flight 182," he said.

It is a stunning twist. For years, Crown prosecutors in B.C. insisted Reyat was guilty of murder and conspiracy to commit murder. All along, Reyat insisted he was not.

In an interview with CBC News in 1998 he said, "I didn't make that bomb. I pray for them (the victims) every day. If I knew anything I (would) tell them (the police)."

The Crown and defence presented a joint submission of facts that implies they finally believe Reyat. It says Reyat bought the materials for a bomb, but he thought it was going to be used in India to blow up property. He didn't know it was going to kill anyone.

It also says he didn't build or arm the bomb, and that he didn't put it in the suitcase that made its way onto Air India flight 182.

And it says he doesn't know who did.

That's key because there are questions whether he will testify in the upcoming trial of the two other men accused of murder in the Air India bombing.

His lawyers say he did not trade evidence for this plea bargain.

Lawyer David Gibbons says Reyat feels great remorse for his role in the terrorist attack and the effect it had on hundreds of families.

"He thinks about it every day. Remorse is not a word large enough to get near what he feels for their sorrow, and it falls on deaf ears sometimes. It's a huge tragedy," said Gibbons.

It is a tragedy that wiped out entire families and left others devastated.

The victims' families are now struggling to come to grips with a five-year sentence.

The courts say Reyat will have served a 25-year sentence given the time he's been behind bars awaiting extradition awaiting the Air India trial, and for his other manslaughter conviction.

The other conviction is for the bombing at the Narita airport in Japan that killed two baggage handlers on the same day as the Air India explosion.