The New Jersey State Police sergeant who shot his ex-girlfriend and her new beau before turning the gun on himself manipulated departmental rules restricting overtime to draw a salary of over $400,000 per year, details in a lawsuit allege.

Sgt. First Class Ricardo Santos, 45, committed the heinous slayings after stalking and harassing his ex, 33-year-old veterinarian Lauren Semanchik, according to cops.

The bitter ex followed Semanchik from her job to her home in Franklin Township, N.J. on Friday night and was lying in wait for her new boyfriend, firefighter Tyler Webb, 29, to pull into the driveway.

Santos then killed them both in the house, before he drove some 50 miles away to a Piscataway park where he parked his 2008 white Mercedes and took his own life, prosecutors said.

Semanchik’s father found her body Saturday morning, one of the victim’s sisters told The Post.

But less than two years ago, Santos was allegedly flying high, earning approximately four times the average salary of an NJ state trooper, according to GlassDoor figures.

In a 2023 discrimination lawsuit against the State of New Jersey, the New Jersey State Police and three members of the department’s top brass, fellow state trooper Claire Krauchuk alleged she was penalized after she divulged that Santos had been cheating the department’s overtime rules.

Krauchuk reported Santos for violating standard operating procedure by “adjusting his hours within the e-daily system” so he could get around a restriction capping overtime at six hours, the suit alleges.

By using this method, Santos — who was not mentioned in the suit outside of this context — was able to juice his salary to the tune of over $400,000, according to the suit, which was brought by four current and former employees of the department.

Santos had not been charged with any wrongdoing, the lawsuit noted.

After reporting Santos, Krauchuk was removed from her post in the Executive Protection Unit and from Governor Phil Murphy’s detail, in which Santos had also served.

Santos and Semanchik dated for approximately three months before she ended things last September.

After the break-up, Santos allegedly wouldn’t stop contacting her, to the point her mother, Jennine, attempted to file a restraining order against him with the Franklin Township Police, according to NJ Advance Media.

However, no restraining order was ever granted.

Franklin Township Police did not immediately respond to a message from The Post asking about the alleged attempt at securing a restraining order or whether one was denied.