As the investigation into the 27-year-old Connecticut man who is accused of fatally shooting a 16-year-old girl he was dating unfolds, police now believe the killing happened after she threatened to tell his girlfriend about their sexual relationship.

According to NBC Connecticut, Dominique Pittman was fighting with Evalyce Santiago in his car when the teen threatened to reveal the nature of their relationship to the woman he’s been seeing for six years and has three children with. Additionally, this woman happens to be the aunt of Evalyce.

When Pittman was initially questioned by investigators after the shooting and car accident on Monday, he blamed the shooting on another man in the car whom he described as Evalyce’s boyfriend.

However, the inconsistencies in his story led him to later admit that only he and Evalyce were in the car together.

Pittman then said Santiago had a knife and started yelling at him about borrowing money from him and him buying her a winter coat. He then claimed she began cutting a key fob from his key chain and took a gun from the center console of his vehicle. Pittman said the two began fighting over the gun when it went off, causing him to crash.

Police found Evalyce in the passenger seat of the car with several gunshot wounds to the head.

During questioning, officers discussed the possibility of Santiago being pregnant and finding traces of his DNA, which forced Pittman to admit having a sexual relationship with the teen until November, according to police paperwork.

At that point, Pittman said Santiago had been FaceTiming him to pick her up and threatened to tell his girlfriend of six years about their sexual relationship, according to the arrest warrant application.

They got into an argument, fought over the gun and he pulled the trigger and shot Santiago twice in the head, the court records state.

Santiago’s family members said they did not know the teen was dating Pittman, and they only knew of his relationship with Evalyce’s aunt.