The Natrona County District Attorney's Office on Thursday filed a 14-count indictment against a man who allegedly sexually assaulted four girls over the past 17 years.

William Kenneth Hall, 45, is charged with four counts of sexual assault against a 13-year-old Natrona County girl this summer, one count of possession of child pornography, one count of making child pornography, and six counts of taking indecent liberties and sexual assault on three girls from January 1999 through December 2002.

All 14 counts are felonies. If convicted on all counts, Hall could spend the rest of his life behind bars.

Hall was in Natrona County Circuit Court on Thursday for a preliminary hearing regarding some sexual assault charges, according to court records.

But those charges were dismissed because of the new indictment. Hall's bond was set at $100,000. He has been in custody since August on other issues.

The case began on Aug. 26, when a county resident told a sheriff's deputy she believed Hall was having an inappropriate relationship with a relative, according to the deputy's affidavit filed in Natrona County Circuit Court on Thursday. The woman said Hall was trying to get the girl to send him photographs of her in her underwear, hugging her at odd times, and entering her bedroom frequently for unknown reasons.

On Sept. 1, the girl was interviewed at the Children's Advocacy Project. She said Hall told her she needed to take nude photographs of herself on his cell phone as payment for him helping her with her chores where they lived on Zero Road. Hall told her to take more photographs of herself or he would show the previous photos to family and friends. He also threatened to distribute the photos if she did not let him sexually touch her.

On Sept. 3, sheriff's investigators contacted Hall at work, and he agreed to talk to them. Hall recounted events that were consistent with the girl's story. He was arrested and booked into the county jail.

Hall gave his two cell phones to investigators, but a search could only access one of them. That one phone did have photographs of the girl naked.

A Wyoming Department of Family Services (DFS) investigator helping the Sheriff's Office located three DFS reports from 2003 to 2004, which indicated Hall had sexually assaulted three other girls. One of those girls was born in 1990, and two were born in 1988.

A Glenrock police officer interviewed the girls on April 10, 2013. The girls, who would have been in their early teens in the late 1990s and early 2000s, said Hall sometimes gave them alcohol and had sexual intercourse with them multiple times, according to the affidavit.

In 2003, a Natrona County Sheriff's investigator and a DFS investigator interviewed Hall, who admitted he had sexual relationships with at least one of the girls when he and they lived on Emerald Acres west of Casper, according to the affidavit. But the affidavit does not disclose why apparently no action was taken against Hall until this week.

On Tuesday and Wednesday, the sheriff's investigator interviewed the three girls, who said they were between 11 years and 13 years old when the assaults occurred. They said Hall would give them alcohol, have sex with them, and force them to touch each other sexually.

Hall will have another preliminary hearing within a few weeks to determine whether this case will be bound over to Natrona County District Court for trial.