It was a tragedy that shocked the Central New York community and beyond.

David Renz murdered a woman and raped a young girl after attacking them outside Great Northern Mall back in 2013.

Thanks to two men, the 10-year-old got the help she needed.

One of those good samaritans sat down with our Brittani Moncrease Thursday.

Bill Cregg of Cicero says it's a day he'll never forget.

He and another motorist found the victims where Renz left them...on Verplank Road.

47-year-old Lori Bresnahan was stabbed multiple times and later died.

Renz had actually been arrested before for child porn and was forced to wear an ankle monitoring bracelet.

However, investigators learned that he tampered with the bracelet more than 40 times, learning how to quickly disassemble and reassemble it in less than a minute.

Now, Cregg has devoted his time to making sure there’s a quicker response to bracelet tampering and holding law enforcement agencies and manufacturers responsible.

He says Renz's case isn’t the first or last time this has happened.

“I think how it’s happening is that there’s no standard operating procedures, nationally on what to do, how to report and then if the tamper alert is gone, what are the requirements of probation to do to follow up on those reports...We need to standardize this so that if this tamper alerts happen, these probation officers have to do this,” said Cregg.

Bill will appear on ABC’s 20/20 Friday night to talk about his efforts. 

Renz is serving a life sentence without the possiblity of parole.