Indiana Authorities Charge Man with Rape, Murder of 1-Year-Old Shaylyn Ammerman

The doctor who performed the autopsy on murder victim Shaylyn Ammerman's remains characterized the toddler's alleged rape and strangulation as "the worst case of sexual trauma" she has ever encountered, according to court records obtained by PEOPLE.

The 1-year-old girl's body was found Thursday night next to the White River in a remote section of Gosport, Indiana. Shaylyn was last seen on Tuesday night inside her father's home.

In court documents filed Monday morning, prosecutors allege that 22-year-old Kyle Parker snatched Shaylyn right out of her crib and then drove the child to an isolated area where he raped her in the front seat of his car.

Court records claim Parker – who has been charged with rape, murder, child molesting, kidnapping, strangulation, aggravated battery, obstruction of justice, failure to report a dead body and unlawful disposition of a body – was invited to Shaylyn's father's home the night she vanished.

According to police, Parker and Shaylyn's uncle, Adam Ammerman, had just become friends. Adam and Justin Ammerman, Shaylyn's father, share a home, according to investigators.

According to the documents, Parker and Adam were drinking alcohol and watching a movie. Adam allegedly told police he fell asleep but awoke to the sound of the front door closing. He allegedly told detectives he peered out his bedroom window and watched Parker heading for his car, "carrying something." Authorities say Adam subsequently passed a polygraph test.

Prosecutors say Parker initially lied to investigators about his alleged involvement in Shaylyn's death, allegedly telling them it was Adam who killed her and then asked him to help dispose of the child's body.

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Parker allegedly told investigators he agreed to help his friend. He allegedly later told police where they'd be able to locate the girl's body, the documents state.

When confronted with Adam's positive polygraph results, Parker allegedly began to cooperate, confessing to police that he acted alone to kill the girl. He allegedly admitted to using bleach to clean evidence on Shaylyn's body.

The results of Shaylyn's autopsy revealed "injuries consistent with a violent sexual assault," according to court records.

Parker allegedly told police Shaylyn was alive and clothed when he kidnapped her, and confessed to suffocating her with a blanket he kept in his car.

Dr. Donna Stewart, who conducted the autopsy, told police, "This was the worst case of sexual trauma she had seen in her career."

In court records, detectives claim they interviewed several of Parker's friends, who all allegedly claimed the suspect preferred "pornography of a violent nature" and expressed interest in girls in their early teens.

Parker appeared in court on Monday, entering a plea of not guilty to the charges against him. He is being held without bail and has a second hearing scheduled for late May.

Shaylyn's funeral is scheduled for Wednesday at the Christian Life Center in Spencer, Indiana, authorities confirm.