On the night of November 16th, 2012, a thirteen-year-old girl in a quiet Ohio suburb called 911 while her mother was being stabbed to death. The person holding the knife was an eighteen-year-old foster daughter named Sabrina Zunich. And for ten months, that's where the story seemed to end; a troubled teenager, a horrific act, a grieving family.

Then Sabrina started talking.

What came out was a case that gets darker the deeper you go: a 41-year-old man who spent months grooming a vulnerable foster child in his own home, coaching her on which knife to use, and then went to work while she carried out what he'd spent months preparing her to do...before collecting $785,000 in life insurance and buying a boat.

This week on Murders & Minivans, we're covering the murder of Lisa Knoefel — a child sex crimes social worker who spent h ...