PITTSBURGH (KDKA) — An East Pittsburgh teenager pleaded guilty Monday in the stabbing death of her mother.

Catherine Grier, 19, pleaded guilty to one count each of voluntary manslaughter, abuse of a corpse, conspiracy and tampering with evidence in the death of her mother, Brenda Johnson.

Johnson, 58, was found dead in her Bessemer Avenue apartment on June 23, 2016, one week after Grier stabbed her several times during an argument.

Grier told police she became scared and called her boyfriend Keith Blackman, 23.

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Blackman came to the apartment and allegedly helped put Johnson’s body inside garbage bags.

He was charged with tampering with evidence and abuse of a corpse.

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