( 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 attorney , though it was n't immediately clear who that would be . CNN 's Lorenzo Ferrigno contributed to this report .
David J. Renz is accused of killing a librarian and raping her 10-year-old daughter . He abducted the pair as they left a gymnastics class in upstate New York , police say . Authorities say he managed to take off an electronic tracking device before the attack . Probation office was not alerted because he reconnected the anklet so fast , officer says .