SALT LAKE CITY—A Utah doctor convicted of murder in the bathtub death of his wife wants a new trial, saying cellmates lied when they testified that he confessed to the killing to them.

Authorities said Martin MacNeill gave his wife drugs prescribed after cosmetic surgery and left her to drown in the bathtub of their home so he could begin a new life with his mistress. Experts said she had painkillers, Valium and sleeping pills in her system and likely drowned in the tub, while MacNeill's attorneys tried to prove she could have died of natural causes.

The trial became national news with the testimony from jailhouse snitches, doctors who said MacNeill pressured his wife into plastic surgery and convinced them to prescribe her the drugs, and a mistress MacNeill introduced as a nanny soon after his wife's death.

The only evidence of homicide came from the two inmates, attorney Randy Spencer said, and he contends that evidence shows they lied in exchange for lighter sentences.

Jurors, however, have said publicly they considered the inmates untrustworthy and disregarded their testimony.

MacNeill has maintained his innocence, and the court documents filed in his request for a new trial also reveal he left a suicide note and slit a major leg artery with a disposable razor on Dec. 5. Officials at Utah County jail intervened to save his life.

MacNeill faces 15 years to life in prison on charges of murder and obstruction of justice. His sentencing, which was set for Tuesday, will be delayed by the appeal.

Spencer said the evidence of perjury comes from emails and transcripts of phone conversations a key inmate traded with his mother and a Utah County investigator. They show Michael Buchanan embellished his accounts of what drugs MacNeill used to kill his wife, and that he hid the fact he expected to win an early release on a drug conviction, Spencer said.

Buchanan picked up facts from cable TV coverage, Spencer said in the Dec. 27 motion to strike MacNeill's conviction.

MacNeill served time with Buchanan in a federal prison in Texas where the doctor was held for identity theft before his 2012 arrest on a murder charge.

Buchanan was identified only as Inmate No. 1 at the trial, but has since been released from prison and identified in court papers.

He testified that MacNeill confessed to drugging his wife and holding her head under water in the tub. He insisted under cross-examination he would not receive a deal or early release for his testimony.

Emails show Utah authorities were successful in getting Buchanan released two years early Dec. 13, little more than a month after MacNeill was convicted.

"Mr. Buchanan was a very important witness," Utah County investigator Jeff Robinson wrote Nov. 15 to federal prosecutors in Knoxville, Tenn., where Buchan was convicted of a drug charge. "I highly recommend and encourage leniency."

Prosecutors say they're confident November's conviction will stand.

"We're looking forward to responding to these allegations," Utah County prosecutor Chad Grunander said. "We've got truth on our side, the rule of law and the jury has spoken."