Updated

Probation officials say they're investigating how a man charged with possessing child pornography managed to cut off his electronic monitoring bracelet before carjacking a woman at a New York mall, fatally stabbing her and raping her 10-year-old-daughter.

The attack happened Thursday night at a mall in the Syracuse suburb of Clay. Police say David J. Renz abducted the pair as they left gymnastics class.

Renz was charged in January with possessing child pornography. He was released after agreeing to stay at home at night with an electronic monitor and away from any place he might encounter children.

Executive Assistant U.S. Attorney John Duncan says officials are investigating whether Renz was able to get around an alert that is supposed to go off if the ankle bracelet is removed.