(CNN) -- A man accused of killing a school district librarian and raping her 10-year-old daughter in upstate New York had removed an electronic tracking anklet before carrying out the attack, police said.
David J. Renz, 29, of Cicero, is accused of abducting the 47-year-old mother and her daughter shortly before 9 p.m. on Thursday as they left a gymnastics class, state police said.
He tied up the mother and raped her daughter in their vehicle, state police said.
He then drove the car a short distance down the road, police said, where the librarian was fatally stabbed.
The girl managed to escape the vehicle and flag down a passing motorist for help.
Her mother was declared dead of multiple stab wounds at the hospital. The girl is still being treated for the injuries she sustained in the attack.
Renz -- who police said was arrested after trying to flee the scene through the woods -- has been charged with rape, kidnapping and murder.
He had been ordered to wear the electronic tracking device on his ankle while awaiting trial on child pornography charges, Matt Brown, chief probation officer of the Northern District of New York, told CNN Friday.
Renz was also told he had to be home between the hours of 9 p.m. and 7 a.m., Brown said.
Authorities believe Renz was able to remove the strap to the tracking device and reconnect it quickly enough that the probation office was not alerted, Brown said.
If a tracking device experiences any trauma, such as banging against a wall, a "strap tampering" report is generated, Brown said. However, if the situation is resolved quickly enough, the probation office is not notified.
This meant Renz was able to reconnect the device and leave it in his home before his alleged attack, Brown said.
Renz was remanded at the federal hearing for his probation violation Friday and then charged on a state level with the alleged attack.
He was expected to be appointed an attorney, though it wasn't immediately clear who that would be.
CNN's Lorenzo Ferrigno contributed to this report.