Mack, 43, entered the plea in Natrona County District Court. He also pleaded no contest to one charge of failure to register as a sex offender.
As part of a deal with prosecutors, the other four counts against him — two counts of first-degree sexual abuse of a minor and two counts of second-degree sexual abuse of a minor — were dropped.
The victims in the case are boys and girls between the ages of 4 and 8.
In court, Mack spoke only to answer procedural questions, quietly answering “Yes” or “Yes, sir” from a podium as Judge David Park asked if he pleaded no contest to each charge. Victims’ family members cried quietly and shook their heads during the proceedings.
Mack faces a maximum of 15 to 30 years in prison.
Had his case gone to trial, he faced a maximum of 265 years in prison if convicted of all eight criminal charges, which included four counts of first-degree sexual abuse of a minor, three counts of second-degree sexual abuse of a minor and one count of failure to register as a sex offender.
Police say they began to investigate Mack after the grandmother of one of the alleged victims found five or six pairs of girl’s underwear in his bedroom in November. The defendant had lived at the grandmother’s Casper home, but at the time of the discovery, he had already been arrested on another matter.
The woman spoke with her grandson, who reported being sexually assaulted by Mack, according to a detective’s testimony at a December hearing. Mack had also reportedly stayed at a home next door and is accused of sexually assaulting a girl who lived there.
A friend of the girl’s who spent the night at her home told authorities Mack had inappropriately touched her while the girls watched a movie with him.
Mack lived at a third Casper home from during parts of 2007 and 2008, according to police. A child who lived there said Mack baby-sat and abused her, according to police.
Mack has a 1995 conviction in Natrona County for indecent liberties with a then 6-year-old girl. He served time at Wyoming State Penitentiary in Rawlins.
Following his arrest, Mack was listed on Wyoming’s online sex offender registry. It indicates he was registered on Nov. 12, 2008.
Mack remains held at Natrona County Detention Center while awaiting a sentencing hearing.