A former teacher at a Faribault prep school was charged Monday with sexual misconduct involving six students, more than a decade after school officials confronted the first warning signs of possible misconduct.

Lynn P. Seibel, 70, who taught theater classes and served as a "dorm parent" at Shattuck-St. Mary's, faces 17 counts alleging that he instigated so-called "AP drama" sessions that included group masturbation, other sexually explicit activities and use of pornography. He is currently being held in the Los Angeles County jail on unrelated child porn charges.

Authorities said it was unclear why Seibel's alleged actions didn't come to their attention sooner, given that the school investigated a sexual-abuse allegation against him in 2001 and fired him in 2003 after it found child pornography on his school computer.

The school maintains that it did tell police and county social services about the 2001 allegation, which it said was unfounded, and that it was not required to inform authorities about the pornography.

Police disputed both accounts.

"Clearly they had opportunities to notify authorities that they didn't take advantage of," said Faribault interim Police Chief Don Gudmundson, who was Dakota County Sheriff when the incidents occurred between 1999 and 2003. He said the material found on Seibel's computer "was clearly child pornography [about which] anyone would acknowledge they had obligation to notify law enforcement."

Agent Drew Evans of the state Bureau of Criminal Apprehension (BCA) said the investigation is continuing, and that it's possible that Shattuck could be charged for not reporting the abuse of children.

School officials refused repeated requests for interviews on Monday, releasing only a written statement.

Jill Oliveira, a spokeswoman for the BCA said "investigators did not encounter any conclusive evidence," that would support school claims they told authorities about the 2001 abuse allegations, and Gudmundson said police records showed no clear reports of sexual abuse allegations in 2001.

Gudmundson said the school sent authorities a copy of its attorney's 2001 phone call to police, but that it had so much material redacted that it was unclear what allegedly happened.

Abuse allegations

The alleged incidents involved boys ages 15 to 18. Some took place in Seibel's classroom and others in the dormitory where he lived with his family, according to a complaint filed in Rice County District Court.

Faribault police began investigating Seibel in June after getting a tip from a community corrections agent from Olmsted County. That agent told police that a young man with whom she had been working said Seibel had forced him and other students to touch themselves sexually in front of him. As the scope of the case widened, police called the BCA for help.

While investigating that allegation, police uncovered other former students who said they had been abused, authorities said.

The charges say the six victims gave similar accounts of Seibel's alleged conduct: He arranged sessions, they said, at which he told teenage students how to increase the size of their erections, watched them masturbate and then measured erections with a ruler. Sometimes Seibel touched them sexually, the charges say.

The charges include two counts of second-degree criminal sexual conduct, soliciting a child to engage in sexual conduct, using a minor in a sexual performance, possessing child pornography and 12 counts of fourth-degree sexual contact with students.

Seibel worked at Shattuck St.-Mary's, a college preparatory boarding school for grades 6-12, from 1992 to 2003.

Gudmundson said the investigation was a complex and sensitive case that had investigators traveling from coast to coast to find former students.

"One young man told police: "I don't know how long I have waited for you to come,'" Gudmundson said.

Seibel had most recently been living in Los Angeles. He also was convicted in 1989 for soliciting or engaging in lewd conduct in a public place in Los Angeles County, records show.

Seibel also is a professional actor and director who's appeared in movies and TV shows, including an episode of the comedy series "The Big Bang Theory" this year in which he played a senile professor prone to showing up naked in public.

Students vulnerable

Several students who remembered Seibel described him as charismatic and very engaging. But at least one 1996 graduate of the school also remembers the oddity of Seibel frequently walking in on him and others while they showered. "He would come in the shower and stare at you for 30 seconds and try to make small talk or said he was just checking in on you," said the now 35-year-old clinical social worker who asked that his name not be used. "You got used to being uncomfortable. It was part of living here and it became normal. No one complained. We talked among ourselves like it was funny.''

In the two years at the school, the former student said, he never witnessed any touching. The former student, who lives on the East Coast, also remembers at least one time when he and other students watched pornography with Seibel, although he doesn't recall who provided it.

"He talked about masturbation and talked about his sexual experiences in detail. It wasn't uncommon to have that kind of conversation. ... We thought this is weird, but then again you're 16 and it was interesting. I wanted the information. It was normal for a 16-year-old male to be interested in sex and here's an adult that wants to talk to you about it. I didn't feel like it was normal but I still wanted to know."

Although Seibel's "odd behavior" was common knowledge among students, the former student said he doesn't know whether any school administrators or other dorm parents knew about it.

Gregory Janson, a sex therapist and trauma expert at Ohio University, said the six teenage boys victimized were likely vulnerable in some way. He said they would suffer the same symptoms, such as nightmares, hyper-vigilance and emotional numbness, as rape victims or military veterans with post-traumatic stress disorder.

"When bad stuff happens to you as a child or adolescent you don't resolve that until your 20s," said Janson, a former sexuality division chairman at the National Council on Family Relations, headquartered in Minneapolis. "The trauma can freeze you developmentally. You don't have abstract thinking tools at 16 that you do at 25."

Staff writer Mary Lynn Smith contributed to this report. Jim Adams • 952-746-3283