JEROME -- A district judge has ordered a new trial for a Jerome man convicted of first-degree murder 30 years ago.
This comes after new evidence surfaced in the case. Defense attorneys say it calls into question what happened the day Charboneau's ex-wife was killed.
Marilyn Arbaugh was shot multiple times with a rifle on July 1, 1984. Charboneau was found guilty a year later, and he's been serving a life sentence without parole.
"We believe Jaimi Charboneau was convicted fairly, in a fair trial, and that's what we're actually defending in this case," said Deputy Attorney General Kenneth Jorgensen.
Charboneau has appealed the first-degree murder conviction in the past, but a letter written by his ex-wife's daughter is giving him new hope that this latest appeal will be his last.
"There was a packet of documents found at the prison," added Jorgensen.
Inside that packet was a letter from Tira Arbaugh. A district judge says it was mailed to the Jerome County Courthouse back in 1989, but was concealed by state officials for more than 21 years.
"That evidence could have made a difference in terms of his conviction," said Brian Tanner, one of Charboneau's attorneys.
According to court documents, the letter says some of the statements Tira Arbaugh made in court about her mother's death weren't true. Tira died after the letter was written, but in it she says prosecutors told her to lie and conceal evidence.
"And it basically calls into question what happened, and she provides a very different story than what was presented at trial," added Tanner.
Charboneau finally received the letter in 2011. In it, Tira also wrote that she heard her sister fire a rifle the day her mother died, but she says she was told to change her statement by authorities.
In the past, Charboneau admitted to shooting his ex-wife, but said it was in self-defense. He claims someone else fired the fatal shot.
A district judge said the letter is real, adding that it will "shake your faith in all you believe in this case." He also told the court the state tried to squash the evidence by keeping it hidden.
Despite that, the Deputy Attorney General says the evidence against the 55-year-old is overwhelming.
"He (Charboneau) bought a rifle two days before the event. He hitchhiked out to her home. He waited in an outbuilding at the home," said Jorgensen.
But Charboneau's attorney says the letter raises new questions about the investigation that need to be addressed.
"We think it's exceptionally compelling. We think after four years that it's legitimate," said Tanner.
On Tuesday, the district judge assigned to the case issued a ruling vacating Charboneau's conviction and ordering the new trial.
However, that's on hold while the Attorney General's Office appeals the judgement.
Attorneys say it could take two years for this all to play out with the Idaho Supreme Court.
Right now, Jaimi Charboneau is being held at the Idaho State Correctional Institution.