Updated

Prosecutors say a Northern California teen accused of killing her mother has reached a deal that will have her pleading guilty and testifying against her former boyfriend.

Fifteen-year-old Tylar Witt and 20-year-old Steven Colver are accused of killing Witt's mother, Joanne Witt, in her El Dorado Hills home last year.

Joanne Witt had accused Colver of statutory rape.

El Dorado County prosecutors announced Friday that Tylar Witt will plead guilty to first-degree murder with special circumstances of lying in wait and killing a witness.

Prosecutors say she also has agreed to testify against Colver. Once she does, prosecutors will drop the special circumstances and reduce the murder charge to second-degree.

Witt would then be sentenced to 15 years to life, instead of 25 years to life.

Colver has pleaded not guilty.