Donte Graves, 18, accused of murders in 2008 and 2013

Police believe an 18-year-old D.C. man is responsible for two murders, more than four years apart.

ABC7 News has confirmed with multiple sources that Donte Graves, who is accused of killing Tyrone Joyner over a coat two weeks ago, was also arrested for killing attorney Mark Blank, 56, in Southwest D.C. in 2008.

Joyner, 22, was shot and killed four blocks from Nationals Park, police say.

In October of 2008, D.C. police say Blank was walking home on 6th Street near the Southwest Waterfront carrying groceries when three teenagers, ages 13, 14, and 15 robbed him and beat him. Blank's injuries were so severe he died 10 days later.

A friend wrote in an eulogy for Blank, "The teenagers who destroyed his life did not know he grew up as poor as them. They did not know he grew up without a father, with no family except his mother. They did not know he was gentle and kind. They did not care."

According to sources, Graves was of one those teenagers.

Tyrone Joyner's uncle wonders what would have happened if Graves had been charged as an adult back then, or if he had served more time in the juvenile system.

"He probably would've been incarcerated where he should have been, because I don't think anyone should get away with murder," the uncle says.

Because the accused killer Graves was a juvenile at the time of the first murder, the Department of Youth Rehabilitation Services wouldn't comment, so it's unclear how much time he served.

But Graves started popping up during ABC7's search of court records in 2012.