(MOUNT PLEASANT, S.C.) -- A 19-year-old man who allegedly stabbed a Walmart employee to death in 2011 pleaded guilty Monday to voluntary manslaughter, The Post and Courier reports.

Darius Green is now set to spend the next 25 years in prison. Green said he stabbed 20-year-old David "D.J." Moultrie in front of the Mount Pleasant Walmart on Sep. 28, 2011, but he refused to explain to the victim's father why he did it.

Green was initially charged with murder, but was able to plead to a reduced charge of voluntary manslaughter that the judge accepted, the paper says.

Lawyers for Green said he was expelled from several schools and displayed a lot of angry as well as threatening behavior. He reportedly has an eighth-grade education, according to The Post and Courier.

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