The defendant waffled, the prosecutor looked exasperated, the defense attorney intervened and the judge weighed in.

Finally, after more than an hour of whispers and negotiations, Damon Michael DiMartino admitted he was guilty of prostituting a Forest Lake girl.

His plea Tuesday, which he said he was making of his own free will, came just as his trial was to begin in Washington County District Court. The jury waited outside the courtroom door as DiMartino, 40, dabbed his eyes with a tissue before agreeing to a 20-year prison sentence for promoting prostitution of a minor.

The unexpected plea came a day after a jury was selected, but it spared the girl from testifying, said Fred Fink, the county's criminal division chief.

"It's a good thing to save her from that," he said.

DiMartino was on 15 years' probation in the summer of 2015 for his most recent of two criminal sexual conduct convictions when he began forcing the girl, then 17, to strip for men.

On Oct. 14, 2015, he drove her from Forest Lake to a hotel in St. Paul to meet a man for sex. That became the crime for which he was convicted.

Prosecutor Imran Ali, of the Washington County attorney's office, asked DiMartino a series of procedural questions to verify his guilt for the court record. DiMartino at first denied knowing the girl was younger than 18.

"Did your relationship evolve with her to where, as you say it, you would set up jobs for her?" Ali asked.

DiMartino denied selling the girl for sex. "That was the result," he said, implying he didn't know what happened.

Murad Mohammad, DiMartino's attorney, got him to admit he didn't prohibit the girl from having sex.

"I assumed it, I didn't witness it," DiMartino said.

Judge John McBride then spoke. "You knew very well that you were promoting her as a prostitute?" he asked the defendant.

"Yes," DiMartino said quietly.

He agreed to the full 20-year penalty, acknowledging it could run consecutively to other prison sentences.

McBride revoked bail, sending DiMartino back to jail until his Oct. 7 sentencing.

Fink said the sudden plea was unusual. In a 40-year career as an attorney, he said, such a thing had happened "maybe half a dozen times."

According to the criminal complaint, the girl told police that in June 2015, after a dispute with her mother, she began living with friends.

She met DiMartino at a party and began seeing herself as his "property" after he supplied her with drugs and alcohol. She began stripping on party buses and later performed "tricks" on DiMartino's orders.

The girl was afraid to identify DiMartino, but she pointed to him as her pimp nicknamed "D" after Forest Lake police showed her a photo, the charges said.

Kevin Giles • 651-925-5037