PORTLAND — A Portland jeweler who taunted a black woman in a restaurant is the first person in Maine convicted of a federal civil rights violation arising from a racial incident.

Thore Aatlo, 32, could face up to a year in federal prison. He was convicted Thursday.

JoAnna Williamson told U.S. Magistrate Judge David M. Cohen that Aatlo approached her at Rosie’s tavern on Feb. 2 and began what at first was a cordial conversation.

But Aatlo soon began to ask her repeatedly what she, “a minority,” was doing in Maine. Eventually, she testified, he told her that she “should go back to the ghetto with all the other lowly black niggers.”

“He said, `You know a minority could get burned out here,’ ” Williamson said. “I said, `Who would do a thing like that?’ Then he said, `I will. I’ll burn your house down.’ ”

In reaching his verdict, Cohen rejected Aatlo’s primary defense that he was too drunk to have known the effect of his actions on Williamson, a 38-year-old stockbroker.

Aatlo’s lawyer, Scott Lynch of Lewiston, also argued that his client’s threats were not specific enough to be illegal and that they were “mere words” and thus constitutionally protected.

Aatlo remains free on bail pending sentencing, probably this summer. He also faces two misdemeanor charges in state court in connection with the incident.

The conviction comes at a time when local, state and federal officials throughout Maine have focused public attention on bias crimes against minorities.

First Assistant U.S. Attorney John S. Gleason called the Williamson case one of the most important of his career.

“This kind of conduct really goes to the heart of what this country’s all about,” he said after the verdict.