AUGUSTA — A former captain with the Augusta Fire Department left court in handcuffs Friday after a jury found him guilty of having sex with a 15-year-old girl at his home in Manchester between April 2007 and April 2008.

The same jury cleared Robert G. MacMaster, 40, formerly of Manchester, of three other charges of sexual abuse of a minor and one count of gross sexual assault.

Justice Robert Murray ordered MacMaster held without bail pending a sentencing hearing later this month. MacMaster had been free on bail prior to the two-day trial in Kennebec County Superior Court. A conviction on sexual abuse of a minor carries a maximum penalty of five years in prison.

MacMaster had been accused of having sex with the underage girl both at his family’s home in Manchester, where she also lived occasionally, and at a city fire station between April 7, 2006, and April 6, 2010.

When MacMaster testified Friday he said he and his family now live in Lincoln.

MacMaster repeatedly and vehemently denied having sex with the girl at a city fire station or in a firetruck, as the girl testified on Thursday. The jury cleared MacMaster of the charges stemming from the alleged fire house incidents.

She testified she was 14 years old when they initially had sex.

He said the two waited until the girl was 16 — the legal age of consent — to have sex. Both he and the girl testified that the initial encounter occurred in his Manchester home while his wife and two children slept upstairs.

The prosecutor, Assistant District Attorney James Mitchell Jr., said MacMaster had functioned in the role of parent for her and violated the law by having sex with the girl even after she turned 16.

Outside the courthouse after the verdict, Mitchell praised the girl for going through the trial. “It is not an easy thing to do,” he said.

He said he and District Attorney Evert Fowle will begin putting together a sentencing recommendation for the court.

Earlier on Friday, MacMaster said he and the girl, who is now 19 and living in Warren, met through her sister in 2007, but the relationship didn’t become romantic until later.

He said he was in love with the girl, and even after they broke up last October, he tried to get back together with her.

He bought her a car last summer and purchased clothing for her and gave her cash last fall, a year after he lost his job as a city firefighter/paramedic and his wife and children were receiving public assistance.

He said he most recently was attending college.

“Pretty much (the girl) got whatever she wanted,” he said. “I took my tuition from my next semester in college to buy her a car. She was going to pay me back $50 a week.”

The breakup, he testified, came last October after he learned she was dating another man.

During his testimony, MacMaster read aloud a series of text messages from last fall about the end of the relationship and MacMaster’s concluding that the girl had reported him to police. The items had been subpoenaed from cell phone companies.

In them, he threatened to leave. He said on the stand that he briefly contemplated suicide.

“My wife found out about my relationship with (the girl) that I don’t have any more,” he said. “Essentially I have nothing.”

Defense attorney Sean Farris said the relationship between MacMaster and the girl was not father-daughter.

“He moved her in, and they were boyfriend-girlfriend during the sporadic times she was there,” Farris argued in closing. “Adopted daughter was a cover story the two of them made up together so people wouldn’t know Mr. MacMaster was having an affair on his wife.”

He added, “The bottom line is (the alleged victim) was not truthful on the stand about 14; she was not truthful about 15.”

After the verdict, Farris said, “Obviously the jury did not believe (the victim’s) testimony that there was sex at 14.”

He said he would look at the potential for an appeal of the verdict.

Earlier Friday, Kenneth Stackpole, a retired Augusta firefighter who frequented the small Western Avenue fire station where MacMaster was assigned, testified he saw the girl at the station several times, once in her pajamas and once with her hair dripping wet as she came from the bathroom carrying a towel.

He said the relationship between the two made him so uncomfortable he would leave and go to another station.

“The interaction I believe was, in my opinion, out of the ordinary, very playful, a lot of physical activity, flirtatious,” Stackpole testified.

MacMaster was a firefighter/paramedic at the Augusta Fire Department for 17 years until he resigned July 7, 2009. He testified about his departure: “I had gotten behind on some bills, made a poor judgment regarding union funds and pretty much was asked to leave.”

MacMaster, who was president of the Augusta Uniformed Firefighters Union at the time, later pleaded guilty to a felony theft charge.

He was sentenced in January to 14 days in jail and was ordered to pay $3,565.14 restitution, which he did.

Betty Adams — 621-5631

badams@centralmaine.com