Canadian prosecutors have told families of the 331 victims of 1985's Air India bombings they will not appeal against the acquittal of two Sikh separatists.
Ripudaman Singh Malik (L) and Ajaib Singh Bagri were cleared
They said they do not believe they have a chance of winning a new trial of Canadian citizens Ripudaman Singh Malik and Ajaib Singh Bagrik.
A judge ruled in March witnesses were not credible and the evidence did not prove guilt beyond reasonable doubt.
The acquittals shocked the families, who then demanded a public inquiry.
Anger and frustration
A review of the trial judge's verdict did not find any legal errors that would have allowed a higher court to overturn the ruling, prosecution spokesman Geoffrey Gaul said.
"The trial judge's judgment is profoundly fact-driven," he told a news conference.
"An appellate court will not interfere in such findings."
Earlier, prosecutors sent an e-mail to relatives saying they had "conducted an exhaustive review and have come to the difficult decision that there are no grounds on which the Crown could launch an appeal".
Relatives expressed anger and frustration at the decision.
Gurdial Sidhu, who lost her sister-in-law, a niece and a nephew, said: "Every day, it was so upsetting. But we had hope that... someone would be punished for the deaths.
"Now there is no hope for anything, nothing at all. It's all very bad, very, very bad."
6 Jun 1984: Indian troops storm Golden Temple in Amritsar to flush out Sikh separatists
31 Oct 1984: India's prime minister Indira Gandhi is assassinated by her Sikh bodyguards. In the ethnic riots which follow 3,000 Sikhs are killed
23 Jun 1985: A bomb blows up Air India Flight 182 as it flies from Montreal to London. 329 people are killed
16 Mar 2005: Ripudaman Singh Malik and Ajaib Singh Bagri acquitted of Air India bombing
Bal Gupta of the Air India 182 Families Association, told Reuters he was "a little disappointed" with the decision but said the families had earlier been warned this might be the case.
In April, Canada's parliament passed a motion backing calls for a public inquiry into the police handling of the case.
Prosecutors had said they were hampered by a decision by Canadian intelligence services to destroy tapped recordings of the suspects.
Two bombs were checked onto flights in Vancouver. One blew up, killing two baggage handlers in Japan as they transferred it to one Air India flight.
The other blew up on Air India Flight 182 off the Irish coast - the worst airborne terror attack until the 11 September attacks in New York and Washington.
Police believed the bombings were in revenge for the Indian government's storming of the Golden Temple in Amritsar, Sikhism's holiest shrine, in 1984.