Jurors only have to conclude an Air India bomb maker lied once out of the 19 occasions the Crown says he was untruthful in order for him to be found guilty of perjury, a judge has instructed.

And each juror doesn't need to agree on which statement made by Inderjit Singh Reyat was false when he testified at the trial of two men charged with mass murder, the judge said.

The Crown says Reyat lied during his testimony at the trial of Ajaib Singh Bagri and Ripudaman Singh Malik, who were charged in two Air India bombings that killed 331 people. Jurors began deliberations Thursday afternoon.

B.C. Supreme Court Judge Mark McEwan told jurors Thursday that each of them must consider the 19 particular false statements Reyat is accused of making.

"Each of you must be satisfied beyond a reasonable doubt that in relation to at least one of the particulars Mr. Reyat gave false evidence at the Malik and Bagri trial," McEwan said. "You do not need to agree unanimously on any one particular."

McEwan urged jurors to consider whether Reyat's answers were reasonable and consistent or contradicted in other parts of his testimony.

The Crown subpoenaed Reyat to testify in 2003, but he was then accused of repeatedly lying while under oath to protect himself, those on trial and others who may have been involved with the bombing conspiracy.

Malik and Bagri were acquitted, and Reyat was charged with perjury in 2006.

Reyat's perjury case is unusual because no witnesses were called and jurors must rely on a recording of his three days of testimony in 2003.

In his instructions, McEwan said in order to find Reyat guilty of perjury, jurors must be convinced he knowingly made a false statement with intent to mislead the court.

Crown lawyer Len Doust told jurors this week that Reyat failed to tell the truth about what he knew about the plot to bomb two Air India planes in 1985 and that he lied to protect himself and others connected to the bombing plot.

But defence lawyer Ian Donaldson said the Crown failed to prove that Reyat was lying to protect himself or anyone else.

Doust said they must use their common sense in deciding if Reyat was telling the truth when he repeatedly said "I don't know," "I don't remember" and "I don't recall" while testifying about matters that would be hard to forget.

Doust, who cross-examined Reyat in 2003, said it's implausible that someone would forget details about gathering bomb parts that led to such horrific consequences.

"This is a disaster of epic proportions, maybe the single-worst disaster in this country," he said.

Reyat testified that Talwinder Singh Parmar, a leader of a Sikh separatist group, asked him in 1984 to collect bomb-making materials but that he didn't know what the explosive device would be used for and he didn't ask.

Reyat's lawyer, Ian Donaldson, said his client, a mechanic, was merely a "soldier" following the orders of the "general" and was hardly a "rocket scientist."

Reyat eventually said the bomb would be used to blow up a bridge or something heavy in India, where he wanted to help people.

But Reyat couldn't say how a bomb could help anyone, and Doust said he only provided a probable reason for the explosive to match what he'd said in an affidavit as part of his manslaughter plea in one of the Air India bombings.

Reyat pled guilty in February 2003 to supplying bomb parts housed in a suitcase that exploded aboard Air India Flight 182, which crashed into the Atlantic Ocean after leaving Montreal for London with 329 people aboard.

He received a controversial five-year sentence for the June 23, 1985 bombing after already serving a decade behind bars for another bombing on the same day when a suitcase meant for a second Air India plane exploded at Tokyo's Narita Airport, killing two baggage handlers.

The Crown maintains both bomb-laden suitcases made their way onto separate planes connecting to Air India planes as part of a conspiracy against the Indian government, which owns the airline.