ALBANY, N.Y. – A man previously charged with having child pornography cut an electronic monitoring device off his ankle before carjacking a woman, fatally stabbing her and raping her 10-year-old daughter, authorities said.

David J. Renz abducted the school librarian and her daughter as they left a gymnastics class at a mall in the Syracuse suburb of Clay, about 150 miles west of Albany, on Thursday night, state police said Friday.

Renz bound both victims, raped the girl and drove a short distance to a spot where the girl escaped and was found by a passing motorist, troopers said. The motorist told 911 dispatchers he saw a man running from the scene, allowing police to quickly send in officers on the ground and a sheriff’s helicopter in the air. Renz was caught a short time later near a wooded area.

It was unclear how the girl escaped or when her mother was killed, authorities said.

“We’re still trying to piece the timeline together,” Trooper Jack Keller said.

The girl was being treated at a hospital Friday. Her mother died from multiple stab wounds.

Renz, 29, had been charged in January with possession of child pornography and allowed to remain free under terms that included staying off the Internet and away from places including schools, parks and arcades.

Renz was arraigned Friday on murder, rape and kidnapping charges and was held without bail.

According to an FBI criminal complaint, agents who went to the North Syracuse apartment where Renz was living in June found in his bedroom four computers that he told them he used to view adult pornography.

Agent Alix Skelton said Renz eventually admitted using the Internet for the past six years to download child porn.