SAN DIEGO -- A woman who claims she was insane when she stabbed her 75-year-old mother to death during a card game in their Normal Heights apartment was convicted Friday of second-degree murder.

A jury on Tuesday will begin considering whether Tomasa Ramirez was insane when she used a 5-inch knife to kill Mercedes Ramirez on Feb. 17, 2007.

San Diego police Officer Meghan Cranston testified that the defendant admitted killing her mother, saying "the voices told me to." Cranston testified that the defendant also said, "The knife is in the sink and I washed it."

Detective Sandi Oplinger testified that the defendant later told her and another detective that she had been playing cards with her mother and voices kept telling her, "Stab your mom. Stab your mom."

Ramirez, 38, told detectives that she got up from the kitchen table, retrieved a knife and stabbed her mother five or six times in the shoulder and back.

If found sane, Ramirez faces up to 16 years to life in prison. If jurors find the defendant was insane at the time of the killing, she would be sent to a state mental hospital.