March 21, 2013 -- Upon his release from custody on federal charges of possession of child pornography, David J. Renz of Cicero, N.Y., was ordered to wear a GPS ankle tracking bracelet as a form of monitoring and supervision.
But it took him less than one minute to disassemble it, take it off his leg, and reassemble it while probation officers remained unaware, authorities said. He had only been wearing the tracking anklet for two months.
Renz, 29, was then allegedly able to leave his home March 14 without detection and abduct Lori Bresnahan, 47, a school librarian, and a 10-year-old girl at a mall in Clay, N.Y.
Renz allegedly bound the woman and raped the girl in the car, state police said. He then drove the car a short distance before allegedly attacking Bresnahan, who died of multiple stab wounds.
Renz, according to police, then fled into the nearby woods, where he was found and arrested. He was charged with first-degree rape, murder and kidnapping, as well as second-degree murder.
Renz's ability to evade his location-monitoring bracelet raises questions about both the security and supervision of the technology.
"We were never alerted that the bracelet was taken off," Chief U.S. Probation Officer Matt Brown told ABCNews.com.
In the federal court system, 51,170 defendants were supervised on pretrial relief in the past 12 months, said a spokesperson for the Administrative Office of the U.S. Courts. Of these cases, nearly 9,000 defendants were placed on electronic monitoring.
"Think of the population we're serving here," said George Drake, president of corrections technology firm Correct Tech LLC. "We're talking about people who are deemed to be acceptable to be released on bond. By definition, these individuals are not the most dangerous people."
Of the decision to supervise Renz through GPS monitoring, Drake said it might have been a bad choice.
"In this case, the U.S. attorney pointed out the bracelet was tampered with at 7:08 p.m. last Thursday evening, and the bracelet circuitry was restored at 7:08 p.m.," said Brown "Obviously, he was able to do this in a very short period of time, so we didn't get an alert from the monitoring company."
"The way these bracelets work is that there is an electronic or fiber optic circuit that runs through the bracelet," said Brown. "As long as it is connected, we know the bracelet is intact, and it's on the person."
Brown said the most common way for someone to disable the tracker is by cutting the strap and then taking the ankle bracelet off. While he could not disclose where Renz left the bracelet when he left his home, he said "nothing has happened like this before."
Brown said Renz disassembled his tracker, which was manufactured by BI Inc., a company that makes offender monitoring technologies. The company has a national contract with the U.S. Probation and Pretrial Services System, he said.
A representative from BI Inc. did not respond to ABC News' requests for comment.
But Drake said the flaw was not with the tracking device nor was it a matter of Renz outsmarting the system. He said the problem stemmed from the protocols of the pretrial unit assigned to monitor Renz.
"As soon as the ankle bracelet comes off the ankle, it creates an event. But the pretrial services in Syracuse decided, for some reason, to not make it an alert unless an event persisted for some period of time," he said.
Drake, who helped to conceptualize offender tracking for high-risk offenders when he was with the New Mexico Corrections Department during the 1980s and 1990s, said there were two different signals transmitted when an offender removed or attempted to remove the ankle bracelet -- an event and an alert.
"You define an alert any way an agency wishes to," he said. "So if an individual removes an ankle bracelet, it is an event and it is recorded as an event. It doesn't have to be an alert unless an agency says, 'I want this to be notified as an alert.'
"Let's say it's only an alert if it persists for more than X number of minutes," he said. "It seems to make sense if you're not an expert in this area, but in reality, it's a very bad decision to make because it allows someone to disassemble the bracelet."
Drake said that, in this case, the event may not have been considered an alert for more than a minute.
"That's very dangerous protocol because it allows for this to happen," he said. "So it's not a matter of the equipment failing. The equipment did exactly what it was supposed to do.'"
Drake, who said he has worn and tested the ankle monitor Renz was wearing -- the BI ExacuTrack One -- said he had never received an indicator of a false alert when testing the technology.
"It's as secure as any device on the marketplace," he said. "In fact, it has some features that other devices don't."
Drake said regardless of the manufacturer, it is not difficult to put together and take apart a monitoring device, especially if you witness a demonstration.
"If you watched me put a device on your ankle and saw how it was put together, you don't have to be a genius to take it off," he said. "I'm sure I can do that in 15 seconds, and almost anybody could."
Drake said if the bracelet is fit properly, it could not be slid off the heel or removed from the ankle without taking it apart.
When you take the ankle bracelet off, "you're damaging all the attachment components," Drake said.
"There are pins and clips and buckles, and things like that," he said. "When you take it off, you're going to leave some visible marks of tampering."
Brown said he could not comment on the condition the tracker was in when it was found, as it was part of the ongoing investigation.
Renz is in custody at Onondaga County Justice Center.
"There was a hole in the security fence and someone found it and walked right through it," Drake said. "They should close that hole."