The Fairfield Police Department said James Taylor, 75, was charged with murder, home invasion, burglary and illegal discharge of a firearm in the incident at a home about 50 miles northeast of New York City.
Authorities said Catherine and James Taylor divorced about 25 years ago but had lived together until May, when he told her to move out. She moved back to a cottage on the property in May and, on Friday, James allegedly got into an argument with his 70-year-old ex-wife and her son, saying "things were going to get bad" for her, FOX61 reported.
"It seemed like there was a buildup in the relationship that it started to boil over," Capt. Robert Kalamaras of the Fairfield Police Department told FOX61.
Police were called Friday to the home after Catherine and her son accused the 75-year-old of trying to steal their pickup trucks, The Hartford Courant reported. No arrests were made, but police said Catherine moved into her son's home after the dispute.
During the weekend the 70-year-old reportedly found out she could track her ex-husband's phone using the "find my phone" app on her iPad because they still shared a family plan for their phone service, according to a police report obtained by the Connecticut Post.
While monitoring his whereabouts on Sunday, she realized he was approaching her home around 9 p.m. and shortly thereafter, he allegedly broke in and shot her to death, the Post reported.
Police said Catherine's son told them James tried to fire a shot at him as he raced into the living room and tackled James while also on the phone with 911 operators.
"He stated in the 911 call that his stepfather had shot his mother," Kalamaras told FOX61. "The son was fighting for his life after that."
Police arrived at the scene and came across Catherine's son pinning James Taylor and subsequently took James into custody.
Taylor was arraigned Monday, where a judge set bond at $2 million. Fairfield Police said the domestic incident remains under investigation.