What happened?

On June 23, 1985, two baggage handlers died when a suitcase exploded as it was being transferred to Air India Flight 301 in the airport at Narita, Japan.

Less than one hour later, another suitcase exploded in the forward cargo hold of airborne Air India Flight 182.

The Boeing 747, which had made contact with the Shannon air traffic control centre in Ireland just moments earlier, plunged into the Atlantic Ocean from 31,000 feet.

British and Irish rescue crews raced to the crash site 240 kilometres off the Irish coast, but all they found were bodies among the wreckage. The crash had claimed the lives of all 329 passengers and crew.

Because both flights had been loaded with baggage in Vancouver, the investigation immediately turned to Canada. It became the longest and most expensive criminal investigation in Canadian history, with an estimated price tag in excess of $100 million CDN.

Under intense pressure to identify the culprits, the RCMP appear to move quickly in the first few months -- especially considering the main suspects in the case had been on their radar in the months before the bombings.

Several Canadians suspected of ties to Sikh militant groups were brought to police attention earlier in 1985, when India's then-prime minister, Rajiv Gandhi, asked Ottawa to ensure the security of his planned visit.

At the time, tensions were still enflamed by the 1984 Indian army raid of the Sikh religion's most holy shrine, the Golden Temple at Amritsar.

After the raid, the Indian government claimed it had found a group of Sikh militants using the temple as a base for terrorist activity. In turn, Sikhs said the assault marked the beginning of a genocide campaign.

Heeding India's request, Canada began monitoring several people including Talwinder Singh Parmar, the British Columbia-based leader of the militant Babbar Khalsa sect. His group was committed to the establishment of Khalistan, an independent Sikh homeland, in the Indian state of Punjab.

Within months, the RCMP raided the houses of several suspected Sikh militants, and wound up laying minor charges against two B.C. residents: Parmar and British citizen Inderjit Singh Reyat.

Police announced that the arrests were made in connection with their investigation of the June, 1985 bombings, but the charges were minor.

Charges against Parmar were later dropped, and Reyat was fined $2,000 before being released.

Reyat later moved to England, where in 1989 he was arrested by police in Coventry, England. After an extradition battle, he was returned to Canada and in 1991, was sentenced to 10 years in prison on manslaughter and explosives charges related to the Narita bombing.

The next breakthrough wasn't until 2000, when RCMP had gathered enough evidence to be confident in pressing a case in connection with the 329 killed aboard Air India Flight 182.

In October 2000 charges of murder, attempted murder and conspiracy were laid against two B.C. men: Sikh cleric Ajaib Singh Bagri of Kamloops and millionaire businessman Ripudaman Singh Malik of Vancouver.

In June of the following year, the RCMP filed seven new charges against Reyat related to both the Narita explosion and the blast on Flight 182.

Setbacks delayed the start of the trial for another two years.

When it finally got underway in February 2003, Reyat surprised observers with a pair of unexpected guilty pleas. In return for pleading guilty to one count of manslaughter and one count of aiding the construction of a bomb, all other charges were stayed and he was sentenced to five years in prison.

Two months later, the trial of Ripudaman Singh Malik and Ajaib Singh Bagri began.

Justice Ian Bruce Josephson said he would bring the case to a close on March 16, when he pronounces his verdict on the eight counts against Malik and Bagri.

The Crown's case hinges on allegations the accused attacked India's national airline in retaliation for the Golden Temple attack. The defence has maintained that not only did the accused not design, construct and plant the bombs, they had no motivation to do so.