PROVO, Utah (AP) — A former Utah doctor accused of hounding his wife to get a face-lift so he could kill her with a lethal combination of prescription drugs acted erratically the day she died and claimed she had wanted the surgery, prosecutors said Thursday in opening statements at the murder trial.

In addition, Martin MacNeill told fellow inmates after his arrest that his wife — a former beauty queen — was a “bitch;” he was glad she was dead; and authorities couldn’t prove he killed her, prosecutor Sam Pead told jurors.

Prosecutors have said the killing was the climax of a twisted plot by MacNeill to carry on an affair with his mistress, who MacNeill invited to his wife’s funeral and asked to marry him weeks later.

The case has shocked the Mormon community of Provo, 45 miles south of Salt Lake City, and captured national attention because the defendant was a doctor.

Pead depicted a scene of bizarre behaviour that began when MacNeill discovered his listless wife in a bathtub and called authorities to his house in April 2007.

“`Why did she have the surgery?'” Martin MacNeill yelled in front of police and paramedics, according to Pead. “`Why did she take all of those medications? I told her not to do it. I’m a doctor. She’s dead. I’ve been a bishop. I pay tithing, and this is the way you repay me?'”

MacNeill was referring to his former leadership position in The Church of Jesus Christ of Latter-day Saints and his payment of dues. He also had been clinical director at the Utah State Hospital but has surrendered his medical license.

Defence attorneys told jurors that Michele MacNeill died from heart disease, not from anything Martin MacNeill had done.

“Martin has made poor choices in his life. He had affairs during his marriage,” defence lawyer Susanne Gustin said in her opening statement.

“Shortly after his wife passed away, he brought Gypsy Willis into his home,” Gustin said. “We may think he’s a total jerk and disgusting. And that’s natural. But decide this case on the facts rather than the emotion.”

MacNeill, 57, was charged in August 2012, nearly five years after his wife was found in the couple’s Pleasant Grove home.

Prosecutors said they will try to prove that MacNeill got a plastic surgeon to prescribe a powerful set of neurological drugs for her recovery. Pead said Martin MacNeill had been giving her those drugs before she died and helped her into the bathtub.

The surgeon, Dr Scott Thomson, testified Thursday that he would not normally prescribe Valium or Oxycodone, among other painkillers and sleeping pills, for recovery, but did so “because Martin was a physician and he asked me for these things.”

Michele MacNeill required only antibiotics, and he advised her to use painkillers sparingly, Thomson said.

Medical examiners couldn’t determine how 50-year-old Michele MacNeill died. They initially ruled she died of natural causes, possibly from a heart disorder, then changed the finding to undetermined.

The uncertainty was one reason it took so long to prosecute Martin MacNeill on the murder charge.

Von Welch, another doctor who examined Michele MacNeill before cosmetic surgery, said her husband was eager to “get things going” and was surprised the couple rejected his advice to put it off until she got her high blood pressure under control.

Michele MacNeill also had depression but was generally healthy, and Welch said he was shocked to hear about her death.

The MacNeills had eight children, and their oldest daughters have been outspoken in their belief that their father killed their mother. Rachel MacNeill and Alexis Somers have gone on national TV with their claims and sat in his court hearings holding up photographs of their mother. They insist his motive was the affair.

The doctor later went to prison on fraud charges, and it wasn’t until his release that prosecutors moved to file charges of murder and obstruction of justice.

Willis also served prison time for fraud. The allegations included forging a document that said they were married on April 14, 2007 — the day of Michele MacNeill’s funeral.

The trial before 4th District Court Judge Derek Pullan is expected to last six weeks.