Tylar Witt, 14 and Steven Colver, 19


PLACERVILLE, Calif. -- A teenager accused of plotting the murder of her mother entered a guilty plea in court today as part of a deal to get a reduced sentence.

Under the agreement, 15-year old Tyler Witt agreed to testify against co-defendant Steven Colver.

Witt and Colver are accused in the 2009 stabbing death of 47-year old Joanne Witt.

The teenager also agreed to tell prosecutors where they hid the knife used in the murder.

Prosecutors alleged Witt spiked her 47-year-old mother's drink with drugs, then called her Colver and let him into the house.

Witt's attorney maintains it was Colver who committed the murder and that girl was acting under Colver's influence.

However, Colver's attorney argues that Joanne Witt was already dead when his client arrived at the home.

Colver was 19-years-old and Witt 14-years-old at the time of the murder.

Prosecutors said the couple was upset after the mother sought statutory rape charges against Colver and gave sheriff's deputies her daughter's diary.