A Seattle court is set to hear the appeal of two prisoners from B.C. who say they were wrongly convicted of brutally murdering one of the men's families 17 years ago.

Sebastian Burns and Atif Rafay were teenagers living in West Vancouver when Rafay's parents and autistic sister were bludgeoned to death at the family's new home in Bellevue, WA.

The two men were sentenced to life in prison with no parole in 2004, after a jury agreed with the prosecution's argument that Rafay had planned the murder to get his parents' money and Burns had carried out the killings.

Their convictions were based largely on confessions they made to undercover officers using the RCMP's famous "Mr. Big" undercover sting, in which suspects are encouraged to brag about their crimes to prove their worth to a supposed crime boss.

But Rafay and Burns have maintained their innocence, and they will argue Friday that their convictions should be overturned in the Washington State Court of Appeals.

The two men insist that their confessions to undercover officers were completely false. In their appeal, they will argue that they were threatened and coerced by people whom they believed to be dangerous gangsters and admitted to the murders out of fear.

Burns's sister Tiffany has made it her personal mission to put an end to the Mr. Big scheme, a police technique that she says amounts to entrapment and results in false confessions. She went so far as to make a feature-length documentary about the scheme, titled "Mr. Big" and released in 2007.

Burns and Rafay's appeal also argues that the judge in their original trial improperly dismissed one juror and refused to dismiss another, and that Rafay's defence lawyer was ineffective.

Arguments in the appeal will be broadcast live online beginning at 9:30 a.m.