A New Jersey State Police sergeant fatally shot his ex-girlfriend and her boyfriend before killing himself, Hunterdon County prosecutors say. 

Prosecutors investigating the murder-suicide in Franklin Township said Sergeant Ricardo Santos killed Lauren Semanchik and Tyler Webb at Semanchik's home in the Pittstown section. 

Authorities said Semanchik, 33, and Webb, 29, were found dead from apparent gunshot wounds on Saturday at the home on Upper Kingtown Road.

Santos was found dead from a self-inflicted gunshot wound inside his Mercedes nearly an hour away, investigators said. 

Suspect stalked ex-girlfriend since breakup last year, family says

Franklin Township police had responded to reports of gunshots and screams in the area on Friday night, but left after being unable to determine where the noises came from.

Semanchik's father discovered his daughter's body and Webb's the next day, the family told CBS News New York.

"She was running away. She was shot in the back," Deanna Semanchik, the victim's sister, said. "She gave so much of her life to other people and she deserved so much better." 

The family said Santos was stalking Semanchik since their breakup almost a year ago. The couple dated for about three months, they said. 

"She tried to block him many times and he continued to call her from restricted numbers. He showed up at her work, that's where the car was keyed. He put recording devices in her home, water in her gas tank. He harassed her left and right," Semanchik's sister said. 

"A lot of agencies failed her. She tried to get restraining orders. Nobody called her back," Jeannine Semanchik, the victim's mother, said. 

CBS News New York learned Santos was part of Gov. Phil Murphy's security detail a few years ago. 

A spokesperson for Murphy released the statement, "We are shocked and devastated by this horrific tragedy. Due to the law enforcement investigation currently underway, we will refrain from further comment at this time."

"He needs to have accountability"

Semanchik was a veterinarian and Webb was a member of the Pinewald Pioneer Volunteer Fire Company.   

"She had the biggest heart," Semanchik's sister said. "She loved animals and she was so good with them."

The Semanchik family said they will continue to seek justice.

"He needs to have accountability. He needs to be taken because he took the cowardly way out by taking his own life," Semanchik's sister said. 

The Hunterdon County Prosecutor's Office urged anyone with information about this case to contact them.