Opening statements began Wednesday in the trial of a Utah man who authorities say injected his 16-year-old baby sitter with a fatal dose of heroin and methamphetamine, then took his infant daughter along when he and his wife dumped the teen's body near a river.

Prosecutors say Eric Millerberg, 38, of North Ogden, had a drug-fueled, sexual relationship with Alexis Rasmussen that led to the girl's death in 2011.

Millerberg has pleaded not guilty to felony child abuse homicide.

His wife, Dea Millerberg, is expected to testify against him this week. She says her husband gave Rasmussen the fatal mix of drugs.

Dea Millerberg has been charged with desecration of a dead body and is awaiting trial. She filed for divorce in 2012, according to court records.

Eric Millerberg hasn't been surprised by his wife's testimony during evidence hearings, but he denies most of what she says, according to his public defender, Randall Marshall, who has not elaborated.

Rasmussen's badly decomposed body was recovered about a month after her death near the Weber River in Morgan County.

Dea Millerberg has testified that the baby sitter became disoriented after being injected once with heroin and twice with methamphetamine.

The girl took a bath to warm her body and rested on a bed, but she wasn't breathing 30 minutes later when the couple checked on her, Dea Millerberg says.

Dea Millerberg, a nurse, says she tried but couldn't revive the girl, then dressed and helped put her body in a footlocker in the trunk of their car.

The Millerbergs left their 6-year-old daughter behind, put an infant daughter in their car and drove off to dispose of the babysitter's body, she said.

Search warrants allege the couple had long supplied Rasmussen drugs in exchange for baby-sitting.