Two men accused of an airliner bombing that killed 329 people have been acquitted after a long, botched investigation, writes Anne McIlroy

Guardian Unlimited

The British Columbia trial judge, Mr Justice Ian Bruce Josephson, found that the bombings were part of a Canadian-based terrorist conspiracy to avenge the deaths of thousands of Sikhs when Indian government troops stormed the Golden Temple in Amritsar in 1984. But he said the crown had not delivered sufficient credible evidence during the two-year trial to convict Ripudaman Singh Malik and Ajaib Singh Badri of mass murder in connection with the attack on June 23 1985.

The acquittals were major news in Canada. People here like to believe the notion that immigrants to Canada leave the violent religious and ethnic minority conflicts of their homelands behind. The Air-India bombing was proof that this is not always the case. It also showed how difficult it can be for Canadian police and intelligence agents to penetrate close-knit communities.

"I began by describing the horrible nature of these cruel acts of terrorism, acts which cry out for justice. Justice is not achieved, however, if persons are convicted on anything less than the requisite standard of proof beyond a reasonable doubt ... The evidence has fallen markedly short of that standard," said Judge Josephson.

Families of the victims say they despair of justice ever being done. They reacted angrily when federal deputy prime minister Anne McLellan said she had no plans to call a public inquiry into how the Royal Canadian Mounted police and the Canadian Security Intelligence Service had botched the investigation.

"This was not an aviation accident, not an in-flight incident. This was murder, pure and simple...the worst case of mass murder in Canada," said Ottawa lawyer Susheel Gupta, who was a boy when a bomb hidden in a suitcase on Flight 182 killed his mother and everyone else on board.

Details of what went wrong in the epic investigation have been revealed sporadically over the years.

There is no doubt that Canada's spy agency failed when it ended surveillance of two suspects just two days before the bombing. That failure was compounded by a decision to follow protocol and destroy surveillance tapes, which were erased despite calls by Mounties to hear the contents. Documents show the RCMP believed the agency was trying to stop the case from going to trial to protect an informant.

For its part, the RCMP was unable to reassure potential witnesses that it could keep them safe after key witness, Tara Singh Hayer, publisher of a Panjabi-language newspaper, was shot at close range and paralysed in August 1988. He was assassinated 10 years later. His murderers remain free.

Only one person has been convicted of the terrorist attack. Inderjit Singh Reyat confessed to providing parts for building the bombs used in the attack, and was sentenced to five years in 2003. He had already spent 10 years in jail for constructing the bomb that killed two baggage handlers at Narita airport in Japan on the same day that Flight 182 went down.

The man many believe masterminded the bombings, Talwinde r Singh Parmar, moved to Canada in 1970. He was arrested in 1985 in connection with the attack, but released because of a lack of evidence. Police in Panjab killed him in 1992.

The victims' families had hoped that Mr Malik and Mr Bagri, who insist they are innocent, would also be sent to jail. Judge Josephson commented that crown prosecutors were unable to produce a single credible witness who could prove otherwise.