A heroic mum was stabbed to death as she tried to fight off the car jacker who had raped her 10-year-old daughter before her eyes moments earlier.
David Renz, 29, allegedly stopped the car and ordered the mum - a school librarian - to drive to a remote part of a parking lot in Syracuse, New York, U.S.
He then used cable ties to bind the mother's and daughter's hands and then raped the child.
Prosecutors said he then drove them a short distance until the car got stuck in a snow bank. He tried to restrain the mother by tying her to a head rest when she fought back and shouted for the girl, whose hands were tied behind her back, to bolt from the car.
The child ran off and was rescued by a passing motorist. But Renz strangled and repeatedly stabbed her mother in the head and chest.
The horrifying details have been revealed in a 37-count indictment that includes a top count of first-degree murder.
"(The mother) died really saving Jane Doe," prosecutor William Fitzpatrick said, using the standard name to identify the child, whose identity is not being revealed because of her age.
"There's no question that she attempted to distract Renz so that little Jane could get away."
The murdered mother's name is also not being revealed in order to protect the identity of the girl.
Prosecutors will seek a life sentence without parole if Renz is convicted.
The attack happened two or three weeks after Renz acquired cable ties and an air pistol that was used to threaten the woman into stopping in a suburban Syracuse mall parking lot as she was leaving a gym class on the evening of March 14.
Authorities said Renz had hours earlier removed and quickly reassembled an electronic bracelet so monitors didn't immediately realise he'd taken it off. He was ordered to wear the device as a condition for being released from jail after his arrest in January on federal child pornography charges.