He was an English teacher who did not last long at any particular school, and as he moved from place to place, Frederic Lyman appears to have left behind a trail of sexual misconduct.

Kent Denver, a private day school in Colorado, on Tuesday released the results of an investigation that found Mr. Lyman had acted inappropriately toward four students while he was a teacher at the school, asking them on dates or over to his apartment, offering them alcohol or propositioning them for sex.

This is the third of the four private schools where Mr. Lyman taught that said he had crossed boundaries with students. On Monday, Phillips Academy, an elite boarding school in Andover, Mass., where Mr. Lyman began teaching in the late 1970s, released a report that said he had “engaged in unwanted intimate touching” of a student during a school-sponsored activity.

Andover’s report did not make clear whether the school was aware of Mr. Lyman’s conduct at the time or if he was given a letter of recommendation when he left. Tracy M. Sweet, director of communications at Andover, said in an email on Tuesday that, “We have not found any record of a recommendation, despite extensive searching.”