Weaver, 16, pleaded guilty to second-degree murder and two counts of robbery. The top charge holds a sentence of 14 years to life, CBS2's Ali Bauman reported.
Majors' father silently walked out of court after Weaver became the third of three suspects to plead guilty to a role in his daughter's death. Prosecutors claim Weaver held the knife that killed Majors.
Web Extra: Read The Complaint Against Weaver (.pdf)
Weaver was being held in a Brooklyn juvenile center since his arrest. In court Thursday, prosecutors claimed the teen assaulted his counselors at the center at least 10 times, shattered two windows and was twice found with drugs.
Weaver's defense attorney said the teen is not the person prosecutors are making him out to be.
"Rashaun is deeply remorseful for his actions and doesn't want his life to be defined by this. It isn't going to be easy, but I think it was the right thing to do. I don't feel good about this plea, it's too high for a kid who was 14 years old when this occurred," said defense attorney Jeff Lichtman.
Lichtman claimed Weaver was the victim of several assaults at the juvenile center .
At the end of the court appearance, someone from Weaver's family called out, "I love you," from the back row.
The teen is due back in court in January.
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