WASHINGTON — An ex-convict accused in the slayings of a wealthy Washington family and their housekeeper was arrested a week after authorities said the family was killed and their mansion was set on fire.

Daron Dylon Wint, 34, was arrested in northeast Washington around 11 p.m. May 21 by members of a fugitive task force and charged with first-degree murder while armed, D.C. police and the U.S. Marshals Service said. Investigators had previously been seeking him in New York City.

Police have not detailed why Wint would want to kill 46-year-old Savvas Savopoulos; his 47-year-old wife, Amy; their son, Philip; and housekeeper Veralicia Figueroa. Three of the four victims had been stabbed or bludgeoned before the fire.

Police said that Wint, a certified welder, worked for Savopoulos’ company, American Iron Works, in the past. Savopoulos was the CEO of American Iron Works, a construction-materials supplier based in Hyattsville, Maryland, that has been involved in major projects in downtown Washington.

Police said that they haven’t ruled out the possibility that other people were involved in the slayings, but no other suspects have been identified.

Wint was born and raised in Guyana and moved to the United States in 2000, when he was almost 20 years old, according to court records filed in Maryland.

He joined the Marine Corps that same year and was discharged for medical reasons, the records show. Following his discharge, he worked as a certified welder, the records show.

The Savopouloses lived in a $4.5 million home in Woodley Park, a neighborhood where mansions are protected by fences and elaborate security systems and local and federal law enforcement officers are a constant presence, in part because Vice President Joe Biden’s official residence is nearby.

Text messages and voicemails from the Savopouloses to their confused and frightened household staff suggest something was amiss in the house many hours before the bodies were found. Their blue Porsche turned up in suburban Maryland hours after the slayings. It too had been set on fire.

DNA analysis at a Bureau of Alcohol, Tobacco and Firearms lab linked Wint to the crime, a law enforcement official involved in the investigation told The Associated Press on condition of anonymity for lack of authorization to discuss the investigation publicly.

During the family’s final hours, someone called Domino’s from their house and ordered pizza. The Washington Post reported that the DNA was found on a pizza crust. At a Domino’s about 2 miles (3.2 kilometers) away, a worker told the AP that a pizza was delivered from there to the mansion that day.

Wint was convicted of assaulting a girlfriend in Maryland in 2009, and he pleaded guilty the next year to malicious destruction of property after he allegedly threatened to kill a woman and her infant daughter, breaking into her apartment, stealing a television and vandalizing her car.

Also in 2010, Wint was arrested carrying a machete and a BB pistol outside the American Iron Works headquarters, but weapons charges were dropped after he pleaded guilty to possessing an open container of alcohol.

Attorney Robin Ficker said Wint didn’t seem violent when he defended him in earlier cases.

A housekeeper who worked for the Savopoulos family for 20 years, Nelitza Gutierrez, told the AP that she believes the family and Figureroa were held captive for nearly a day before they were killed, citing an unusual voice mail she got from Savopoulos and a text message sent from the phone of his wife, telling her not to come to the house.

The Savopouloses had two teenage daughters who were away at boarding school at the time of the slayings. Relatives of the victims have made few public statements and have not returned calls from the AP. Representatives of American Iron Works have repeatedly declined to comment.

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By Ben Nuckols. AP photographer Alex Brandon in Washington and AP freelancer Meredith Somers in Upper Marlboro, Maryland, contributed