(Painesville) - Gripping testimony in the Lake County murder trial of Kevin Knoefel, who's charged with orchestrating his wife's murder.

Taking the stand was 19 year old Sabrina Zunich, the prosecution's star witness.

Kevin Knoefel's foster daughter testified that she stabbed wife Lisa Knoefel dozens of times in her Willoughby Hills home in November 2012, because Kevin instructed her to do it.

Zunich claimed she was in love with Kevin and that they had an ongoing sexual relationship. She told the court that Kevin had threatened to kill himself, if she did not kill Lisa.

Zunich admitted to plotting to kill Lisa twice before, by hiring a hitman and by shooting her with a gun.

Zunich said she had planned to make the stabbing look like a burglary gone bad, and was to text Kevin when the deed was done.

Kevin Knoefel & Sabrina Zunich.

Zunich explained that she went into Lisa's darkened bedroom with a knife while her victim was half asleep, with her first blow striking Lisa in the face. She admitted the repeated stabbings continued even after Lisa was dead.

Investigators maintain Lisa was stabbed 170 times.

Zunich said she didn't like Lisa because her foster mother always made her feel like an outcast, and it brought back memories of being abandoned by her birth mother.

Zunich said she had a history of being treated for depression and for being bi-polar.

The defense characterized Zunich as a manipulative liar, who acted alone, and agreed to testify against Kevin to avoid the death penalty.

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(Photos by Ken Robinson/WTAM)