A one-time supervisor at Dorchester Center's post office has been sentenced to 15 months in prison for lying to criminal and civil investigators in the alleged sexual assault of a co-worker in the office's boiler room.

John Kelley, 46, a former acting manager, was sentenced last week by a U.S. District Court judge on two counts of perjury and one count of a scheme to falsify information, according to U.S. Attorney Michael Sullivan's office. The sentence also carries two years of supervised release.

Kelley's attorney, Boston lawyer Richard Vita, did not return a phone call seeking comment.

The sexual assault allegedly occurred in fall 2000, with the female employee, referred to in court papers as "KD," alleging that she was sexually harassed and ultimately sexually assaulted in the boiler room.

Both of them no longer work at the Talbot Avenue post office.

When the co-worker later brought a civil suit against Kelley, a Saugus resident, a DNA sample showed that semen recovered from the post office's boiler room was Kelley's.

A civil jury found Kelley liable for the sexual battery, awarding "KD" $600,000 in the suit. Kelley has yet to pay the money, according to Sullivan's office.

When interviewed by postal inspectors in October 2000, Kelley said he did not rape "KD" and denied having any sexual contact with her.

As part of a formal Equal Employment Opportunity (EEO) complaint of discrimination, Kelley was interviewed again by a United States Postal Service investigator in July 2001, saying in a written statement, "I have not discriminated against [KD] because of her sex, and I have never subjected her to sexual harassment over a period of time. Furthermore, I never raped her as she has alleged, and I had no personal relationship with her. There was never any sexual relationship between us, either consensual or otherwise."

It was in the course of the civil suit, where Kelley spoke under oath at a deposition in August 2005 and sworn testimony the following November, that Kelley admitted he made false statements to postal inspectors in October 2000 and July 2001.