A new law took effect Monday in Tennessee that requires GPS monitoring of the most violent domestic offenders. Born from an unspeakable tragedy, the law is the first of its kind in the U.S.

On April 12, 2021, Debbie Sisco and her daughter, Marie Varsos, were shot and killed outside Nashville by Marie’s estranged husband, Shaun Varsos, who later took his own life.

Varsos broke into his mother-in-law’s house, where Marie was staying, with guns, zip ties, and battery acid ready to hunt them down.

He had been out on bail after strangling his wife and threatening her with a gun a month earlier.

Alex Youn, Marie’s brother and Debbie’s son, was devastated.

“Two people that I love dearly were just quickly ripped out of my life,” Youn said.

Varsos was considered enough of a threat that the judge could have required a GPS tracking device as a condition of his bail, but he didn’t. Youn believes his mother and sister may still be alive if the judge had required it.

“That’s a question for the judge. It’s one that infuriates me,” Youn said.

Judges can require GPS monitoring as a condition of bail, but often don’t.

Youn turned his pain and anger into a successful push for mandated GPS tracking of aggravated assault offenders in domestic violence cases. Tennessee’s new law is called the Debbie and Marie Domestic Violence Protection Act.

One in four women and one in seven men are victims of domestic violence, according to the CDC.

“When there’s firearms at play, when there’s strangulation, when there’s elevated stalking, [offenders] are more likely to do it again,” said Jennifer Waindle, a deputy director of non-profit Battered Women’s Justice Project.

That’s how GPS tracking could potentially be the difference between life and death. With the technology, victims are notified through a phone app or electronic device when an offender violates an order of protection, such as moving within a certain radius of the victim or breaching an exclusion zone, like their house. When that happens, the victim can receive multiple alerts like texts and emails, while a monitoring center calls law enforcement.

Ray Gandolf, director of business development for Tennessee AMS, is helping to lead the charge on using GPS technology as a safety tool.

“Every second matters,” Gandolf said.

Gandolf said the alerts can allow victims to look for help or find cover. “They can position themselves in a safe place, lock themselves in a place where they have the opportunity to call 911 and to get help dispatched to them immediately,” Gandolf said.

In Tennessee, Youn has made sure the names of Debbie Sisco and Marie Varsos will live on.

“I’m hopeful that other states will potentially sort of look at what Tennessee is sort of doing and take this and implement it in other states as well,” Youn said.

If you or someone you know is experiencing domestic violence, contact the National Domestic Violence Hotline by calling 1-800-799-SAFE (7233), visiting www.thehotline.org or texting “START” to 88788.

Meg Oliver

Meg Oliver is a correspondent for CBS News based in New York City. Oliver is a veteran journalist with more than two decades of reporting and anchoring experience.