Sixty-eight year-old Michael James Angus will spend the next decade in a federal prison after pleading guilty Thursday to a charge of possessing sexually explicit images of minors.

Angus will serve a 10-year sentence, without the possibility of parole, and then spend the rest of his life on federal probation, as part of a plea agreement he made with federal prosecutors Thursday.

As part of that plea, Angus also admitted to engaging in sexual contact or other sexual behavior with a total of seven young girls, age 10 or younger, according to U.S. Department of Justice reports.

The plea agreement means that all charges filed against Angus in Idaho state court — two counts of lewd conduct, one count of sexual abuse of a minor, and five counts of possession of child pornography, will be dismissed.

Ada County Sheriff’s detectives began investigating in late 2011, after getting a report that he had sexual contact with an 10-year-old girl while her family was visiting at Angus’ Star home on October 30, 2011. The parents of the girl also expressed concern for the welfare of another child, an 8-year-old, who often spent time alone with Angus at his home, according to U.S. Department if Justice reports.

Detectives found that girl, who told them Angus he had also taken pictures of her dancing and posing nude when she was in the bathtub.

Deputies then got a warrant to search Angus’ home in November 2011 and discovered child pornography, including sexually explicit images of the 8-year-old girl, whom Angus had cared for off and on for several years, according to reports.

The images were produced on at least four separate dates between July 2009 and September 2011, mostly in or around a bathtub in Angus’ home in Star.

Investigators also discovered hundreds of images of other, yet unidentified minors that had been downloaded from the Internet, including 66 images that are child pornography. The others included naturist (or nudist) images of children as young as two years of age, many of which would be considered “child erotica” to a person with a sexual interest in children, according to reports.

As a condition of the plea agreement, Angus was required to meet with investigators earlier this year and take a polygraph test about any other potential victims. That’s when federal prosecutors say he admitted to having either sexual contact or behavior with five other young girls.

That admission allowed prosecutors to seek a more lengthy prison term under the federal sentencing guidelines, officials said.

Ada County Deputy Prosecutor Jean Fisher said Thursday that resolving the both state and federal cases with the plea agreement will spare the child victims from having to testify in open court and provides a significant and fixed prison term — and a lifetime of parole supervision when he gets out — for the 68-year-old Angus.

“We had a very young victim, who was having a very difficult time talking about the abuse, so we worked federal prosecutors to resolve the case in a way that would protect her and (Angus) would get a harsh penalty,” Fisher said.

“Protecting and rescuing children from sexual exploitation is a critical law enforcement function,” U.S. Attorney for Idaho Wendy Olson said Thursday. “Tragically, in this case, Mr. Angus victimized several young girls before one family contacted law enforcement.”

Olson praised state and federal law enforcement “for their work in securing what may amount to a life sentence for Angus and a resolution that ensures his victims obtain justice without having to testify in open court.”

The case was investigated by the Ada County Sheriff’s deputies who work with the Idaho Internet Crimes Against Children Task Force, with the assistance of agents with the FBI’s Regional Computer Forensic Lab.