FARIBAULT — A former teacher at a boarding school in southern Minnesota was sentenced Friday to more than four years in prison for sexually abusing six male students more than a decade ago.

Lynn Seibel, 71, pleaded guilty to seven counts in July, more than a year after police began investigating alleged sexual contact with students at Shattuck-St. Mary’s school in Faribault.

He was sentenced Friday to 52 months in prison on the most serious count but could be released in less than 2 1/2 years with credit for time served and a possible reduction for good behavior. He’ll then be placed on probation for 30 years, likely the rest of his life. Rice County Attorney Paul Beaumaster said Seibel must also attend sex offender treatment, register as a predatory offender and pay restitution to victims.

“It’s a sad case … that had basically been unacknowledged for such a long period of time,” Beaumaster told The Associated Press. “Bringing it back up is always hard on victims.”

Seibel was charged last October with 17 felony counts for alleged possession of child pornography and the sexual abuse of the six male students from 1999 to 2003.

He pleaded guilty to one count of second-degree criminal sexual conduct, five counts of fourth-degree criminal sexual conduct and one count of using minors in a sexual performance.

A letter from one of Seibel’s victims, who was 16 at the time of the abuse, was read in court, the Faribault Daily News reported.

“I will be struggling with what you did to me for the rest of my life … My world was focused on being a kid, I was just in high school and you scarred me forever,” the letter said. “You will not win the ultimate fight for my life, my heart and my soul — you will pay for what you’ve done.”

Seibel taught drama at Shattuck-St. Mary’s from 1992 to 2003 and lived in one of the dormitories. He was hired despite an earlier criminal conviction for lewd conduct. Seibel was fired from in 2003, after child pornography was discovered on his computer, but police were apparently not informed and he was not charged, authorities said. He had been working as an actor in California before his arrest last year.

The school investigated allegations of sexual misconduct by Seibel in 2001 but said it found no evidence to support the claims. Faribault police opened an investigation in 2012 after a former student reported he had been abused by Seibel in 2001. Five additional victims were identified.

Seibel has taken responsibility, and has acknowledged he encouraged a “naked dance party,” in which boys danced in the shower. On Friday, he apologized to his victims, the Daily News reported.

“I obviously have caused a great deal of harm to a great deal of people,” Seibel said in court. “As a teacher you’re supposed to help, and I betrayed their trust.”

Rice County District Court Judge Christine Long told Seibel there was no excuse.

“You took advantage of your victims’ naivete, immaturity, for your own sexual gratification,” Long said.

Shattuck-St. Mary’s faces two negligence lawsuits filed on behalf of former students who claim Seibel sexually abused them.