A Sandy child care provider is accused of killing a 9-month-old baby by causing what one doctor called "the worst case of an inflicted brain trauma" he'd ever seen in a child.

Jared Daniel Billette, 23, was charged in 3rd District Court Friday with first-degree felony murder in connection with the death of Milo Doxey earlier this week.

According to charging documents, Doxey's mother dropped her son off at Billette's apartment on the 1000 East block of Promontory Way (7880 South) around 3:30 a.m Wednesday. The mother had been leaving the baby with Billette and his girlfriend Brianna Cottrell, 21, on occasion when she needed baby-sitting services, charges state.

Cottrell and Billette woke up at 8:30 a.m. when a 2-year-old girl was dropped off for them to baby-sit. Cottrell then left for work, leaving care of both children to Billette, charges state.

Cottrell called Billette around 11:15 a.m. to check in on him. That's when he told her that Milo was unresponsive, according to charges.

Cottrell left work and returned to the couple's apartment, where she observed Milo on the couch. The baby was not breathing and Cottrell called 911 and the boy's mother.

The child was flown by helicopter to Primary Children's Medical Center where he underwent emergency surgery.

Physician Lori Frasier, an expert in abusive head trauma in infants, examined the baby and found he suffered a "massive, global brain injury," charges state.

The injury was likely caused by "a combination of severe rotational forces and massive impact to the head," Frasier found. She said the baby's trauma could only have been carried out by a person with "adult strength" and couldn't have been caused by an accident.

A pediatric neurosurgeon operated on part of Milo's skull to relieve swelling his brain with hopes the baby would survive. The neurosurgeon called Milo's injuries "the worst case of an inflicted brain trauma in a child" he had ever seen.

Milo died from head injuries on Thursday.

Billette told police he put Milo on the floor of the apartment around 8:30 a.m. when Cottrell left for work. He said the baby -- who can roll and sit up but could not yet crawl or walk --was in the living room watching TV when Cottrell called Billette at 11:15 a.m., charges state.

Billette told police he left the room to speak to Cottrell on the phone, but when he returned to the room the baby was unresponsive. Billette said the baby's eyes were rolled in the back of his head and that he tried to awaken the child, who was gasping for breath, by splashing cold water on his face.

Billette denied that any accident or abuse happened with the baby, according to charges.

Billette is from Washington state and has been living in Utah with Cottrell, his girlfriend, for about a month, Sandy Police Sgt. Justin Chapman said Friday. Cottrell was friends with the baby's mother and trusted the couple to care for her child, Chapman said.

The two recently started babysitting to bring in some extra money, but weren't formal daycare providers, he said.

Billette faces 15 years to life in prison if convicted of murder. His initial appearance is scheduled before Judge Mark Kouris on Oct.14.

He is being held in the Salt Lake County jail in lieu of $1 million bail.

mrogers@sltrib.com