A bomb-detecting scanner beeped at a large suitcase at Toronto's airport, but the bag made it onto Air India Flight 182 anyway.

Antonio Coutinho, testifying at the first-degree murder trial of two men accused of being behind Canada's worst act of terrorism ever, said the beeps meant it could contain a bomb. But he heard a supervisor tell an employee the beeps occurred because of the suitcase's locks.

Coutinho said he heard beeps even when the sides of the suitcase were scanned.

Ripudaman Singh Malik and Ajaib Singh Bagri at the Air India trial (CP FILE PHOTO)

He was testifying at the B.C. Supreme Court trial of Ripudaman Singh Malik, 56, and Ajaib Singh Bagri. They face a total of eight charges, including attempted murder and conspiracy.

Besides the Air India deaths, they are also charged in the deaths of two baggage handlers at Tokyo's Narita airport. A suitcase bomb exploded there 54 minutes before the one that blew Flight 182 – travelling from Toronto to London – apart over the Atlantic Ocean near Ireland. That bomb was intended for Air India Flight 301.

Indirjit Singh Reyat, a former co-accused, pleaded guilty in February to manslaughter. He was sentenced to five years on top of the 15 he had been in custody for his role in the Narita bombing.

Coutinho's testimony is interesting because the Crown's theory is the bomb-laden suitcases targeted at Air India Flights 182 and 301 originated in Vancouver.

A former CP Airlines employee testified she checked in two suitcases at Vancouver International Airport believed to contain bombs.

She put pink tags on them directing them to Air India flights in Toronto and Tokyo.

Coutinho said the beeping suitcase in Toronto had a reddish-brown tag and was destined for Mumbai.

Another witness, Richard Bildy, testified about the laxness of security at Toronto's airport.