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The man allegedly responsible for the quadruple homicide at a Washington mansion last month has a cousin who was fired from American Iron Works, the company owned by slain patriarch Savvas Savopoulos, CNN has learned.

Daron Wint, the homicide suspect, worked there from 2003 to 2005. Wint’s cousin worked there as well until being fired in 2005, and sources tell CNN that the cousin then threatened to burn the place down. The company obtained a restraining order barring the cousin from the premises, the sources say.

Law enforcement officials now tell CNN that Wint’s DNA was found on other parts of the crime scene as well.

Police believe Wint killed Savvas, Amy and their son, 10-year-old Philip Savopoulos and their housekeeper Veralicia Figueroa inside the family’s $4.5 million mansion not far from Vice President Joe Biden’s home and several embassies.

Wint is being charged with first-degree murder.

Wint, who was born in Guyana, was also in danger of losing his green card because of prior arrests, CNN has learned.

The Metropolitan Police Department spokeswoman Gwendolyn Crump said it ran Wint’s fingerprints in March in the FBI database, which was supposed to automatically flag ICE, but the immigration officials were never notified, officials said.

“If Daron Wint was arrested in March and (Immigration and Customs Enforcement) never received those fingerprints until he’s arrested for quadruple homicide, it’s an indicator there’s a breakdown in system to me,” said John Torres, former ICE special agent in charge. “Had ICE been notified they would have looked at Daron Wint’s history and undertook a legal review to determine whether or not he was eligible for removal.”

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Police have identified Daron Dylon Wint as a suspect in a quadruple homicide in Washington.

Court documents say that the family was found dead in a mansion set ablaze after Wint allegedly kidnapped and held the family hostage for 18 hours. Everyone from the housekeeper to the young son Philip was brutally beaten and then stabbed, the documents say.

In an exclusive television interview with CNN, Philip’s go-kart coach, Jay Howard, recalled the 10-year-old as “passionate beyond belief.”

RELATED: Father in mansion murders strangled, beaten, burned

Amy and Savvas followed Philip to all his races and completely devoted themselves to his sport, Howard said.

“No matter how he did on track, he would just be smilin’ from ear to ear and it was very contagious,” Howard said.

Philip wasn’t supposed to be home on the day of the murders, Howard said. But after a go-kart accident left him with a mild concussion, he was ordered to a few days of bed rest.

“I mean, obviously wish he wasn’t at home,” Howard said. “But I don’t know. Not somethin’ you really wanna kinda think about. You know, it’s, like, just horrible thing that happened.”

Ten days later, Philip was killed.

CNN’s Evan Perez and Joe Johns contributed to this report.