The dean of students at a South Los Angeles school is under investigation by police for allegedly concealing evidence that one of his colleagues, former Assistant Principal Stephen Thomas Rooney, had a sexual relationship with a student.

The dean, identified by authorities in court as "Mr. Hubbard," came under suspicion after detectives discovered that for more than a year he had kept photos, notes and a scrapbook that documented the relationship between Rooney and a former student at Foshay Learning Center.

Hubbard allegedly received the materials in spring 2007 from a friend of the former student, who had collected them. At the time, the Los Angeles Police Department was investigating allegations that Rooney had a long-term sexual relationship with the student, beginning when she was 15.

School officials said last week that they had put a dean, whom they identified as Alan Hubbard, on administrative leave in connection with the Rooney case.

"He has been removed from the workplace -- that is my concern -- and he will go through the legal process," David L. Brewer, superintendent of the Los Angeles Unified School District, said in an interview Wednesday.

Hubbard, who has not been charged with any crime, did not return calls seeking comment.

When detectives interviewed Hubbard, he told them he was "keeping them for Rooney" and said he didn't know exactly what the items were, said LAPD Capt. Fabian Lizzaraga.

The photos and notes are important because they show that Rooney and the student had a relationship outside of school. In court last week, prosecutors displayed portions of the scrapbook, which included photos showing Rooney and the girl kissing.

Lizzaraga said detectives had not known about the photos until last month, when they demanded that the dean turn over materials in his possession.

The school district has come under intense criticism for its handling of Rooney's case. In February 2007, the LAPD told district officials that Rooney was suspected of having sexual contact with a student. After initially putting Rooney in a desk job, school officials transferred him to Markham Middle School in Watts. He has now been charged with molesting two students there, as well as the former student at Foshay.

The district has launched an internal investigation into the matter, and on Tuesday removed two senior administrators from their jobs for failing to investigate the allegations against Rooney before moving him to Markham.

Rooney, who is being held in lieu of $1-million bail, has denied the charges.

At a preliminary hearing last week, the former Foshay student testified that after Rooney was arrested in February 2007 for allegedly waving a weapon at her stepfather, he instructed her to gather the photos and other materials concerning their relationship. The girl gave the materials to a fellow student, who in turn gave them to Hubbard, Lizzaraga said.

At the time, the student told detectives that she had a sexual relationship with Rooney -- but then denied the relationship to Los Angeles County prosecutors, who that spring decided there was not enough evidence to file charges against Rooney.

She testified in court last week that she went to "Mr. Hubbard" around this time, upset that Rooney might go to jail. She did not reveal the details of the meeting, but said it ended with Hubbard telling her that she should recant her comments to police.

This year, after Rooney was arrested on suspicion of having sex with a student at Markham, the former Foshay student came forward and began cooperating with police. Lizzaraga said she told detectives that Hubbard had a bag of items, including notes and photos. Rooney has since been charged with molesting the former Foshay student and a second Markham student.

In court last week, Deputy Dist. Atty. Darci Lanphere showed the former Foshay student, now 18, the scrapbook photos. Lanphere asked how she felt about seeing them again.

The young woman replied, "It is hurtful but sweet at the same time."

During that testimony, she revealed that she began her relationship with Rooney when she was 15, went on trips with him to New York and San Diego, and in 2006 became pregnant; she later had a miscarriage. The sexual relationship, the student testified, continued even after the police investigation in spring 2007.

In court, Rooney's lawyer, Dmitry Gorin, challenged the credibility of the former Foshay student. Under cross-examination at the hearing, she admitted that she had a fake driver's license that stated she was two years older than she actually is and that she had committed identity theft. She also acknowledged lying under oath last year during an emancipation hearing, in which she had denied having a sexual relationship with Rooney.