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 today.

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 away 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 today. 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. He lost his job at a supermarket, moved in with his mother and hadn’t been able to find other work after his arrest, according to court documents. Federal authorities said he cut his electronic monitoring device off his ankle shortly before Thursday’s attacks.

Renz was arraigned today on murder, rape and kidnapping charges and was held without bail. The lawyer assigned to his case, Ken Moynihan, didn’t return a call seeking comment.

The Associated Press generally doesn’t publish information that could identify potential sex crime victims and isn’t naming the woman to protect the girl’s identity.

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 to a drive on one of the machines, which he turned over to the agents. Technicians determined in November that it had an encrypted hard drive, and Skelton said Renz provided the encryption key. Agents reviewing the drive in December found about 100 gigabytes of child porn comprising more than 500 videos and more than 3,000 images, according to the complaint.

Among the images were two showing sex acts involving prepubescent girls, said Skelton, a member of a unit that targets people involved in online exploitation of children.

Renz was charged on Jan. 9 in federal court with possession of child pornography. On Jan. 29, a judge granted a prosecutor’s request for an extension of the time required for grand jury action so investigators could continue going over “numerous items of electric media” for additional evidence.

Renz, who authorities said had no prior police record, was released after agreeing to stay at home at night with an electronic monitor and away from any place he might encounter children.

But Renz removed the monitor, Executive Assistant U.S. Attorney John Duncan said. Federal probation officials were investigating what happened, including whether Renz was able to get around an alert that is supposed to go off if the ankle bracelet is removed, he said.

Late Friday afternoon, state police turned Renz over to federal authorities, who will hold him for violating the terms of his release, court documents said.

Duncan said the cases against him will continue in federal and state courts.

The federal public defenders lawyer assigned to Renz in the child porn case, James Greenwald, did not return a call seeking comment today.