As the Air India inquiry resumes this week, investigators will be probing why Canadian spies erased wiretap recordings of key suspects in the 1985 terrorist bombing.
It will be the final round of public hearings this year into how the worst terrorist attack in Canadian history was allowed to happen.
The families of the victims have continually been exasperated over unanswered questions about why the tapes were erased by Canadian Security Intelligence Service agents.
Family members have complained that the missing recordings are one of the reasons no one has ever been convicted of the bombing of Air India Flight 182 that killed 329 people.
Both CSIS and the RCMP representatives will be called to testify this week about relations between the two agencies in the aftermath of the bombing.
Mike Roth and Lyman Henschel, both retired Mounties, will take the stand Monday. They are expected to recount the decision by CSIS to erase the hundreds of hours of audio surveillance that the RCMP had intended to use to gather evidence for its criminal probe.
Later in the week James Jardine, a British Columbia court judge and former Crown attorney is expected to speak about how the loss of the tapes affected the court proceedings that followed.
Then CSIS representatives are expected to take the stand to explain things from their end. Retired counter-terrorism boss Jake Warren is expected to be among the CSIS representatives to take the stand.
However, there is no guarantee that this week's hearings will lead to any conclusive answers on the question of the tapes. There have been longstanding differences between the two agencies on what took place regarding the recordings and whether they could have led to a conviction.
Mark Freiman, the chief counsel for the inquiry headed by retired Supreme Court justice John Major, told The Canadian Press the complexity of the issue, and the challenges of transforming raw intelligence data into evidence, will be a key theme at the hearings this week.
Later in the month the inquiry hopes to look at an alleged confession that was given to police by Talwinder Singh Parmar, the head of the militant Sikh separatist group Babar Khalso, and the prime suspect in the attack that killed 320 people.
Parmar was arrested by the RCMP following the attack, but was later released due to a lack of evidence linking him to the crime.
In 1992, Indian police reported that Parmar had been shot dead in the Punjab.
However, there have long been reports that before he was killed, he was captured by police and confessed to being involved in the bombing, likely under torture, and was then put to death.
The matter was expected to be the subject of earlier hearings held in June, but witnesses backed out when Major said he couldn't guarantee their anonymity.
The witnesses returned to India and it was eventually reported in Tehelka, an Indian magazine, that one of the key witnesses to back out, a former police officer, had kept audiotapes and transcripts of the confession.
Parmar reportedly confesses to participating in the bombing, but denies masterminding it.
Questions remain, however, over whether a confession, possibly obtained under torture, could even be used in a Canadian court.
Freiman said those questions will be addressed.
"We'll deal with it in a way that we hope will be responsible," he told The Canadian Press. "But we're not going to avoid looking at issues simply because they're complex, or because they're unpleasant."
The only person ever convicted in the bombing is Inderjit Singh Reyat, a Parmar associate who was found guilty on manslaughter after prosecutors reduced the charges.
Two others, Ripudaman Singh Malik and Ajaib Singh Bagri, were acquitted. Families of the victims were outraged by the verdict.
With files from The Canadian Press
