FROSTPROOF, Fla. (AP) — A 21-year-old college student has been charged with first-degree murder after Florida authorities say he drove to his mother’s home and stabbed her multiple times Saturday because “she got on my nerves,” authorities said.

Emmanuel Espinoza drove about 165 miles (266 kilometers) from the University of Florida in Gainesville to Frostproof, Florida, for a family event. When he arrived at his mother’s, he began stabbing her when she answered the door and then called 911 to confess to the slaying, said Polk County Sheriff Grady Judd.

Elvia Espinoza, 46, was on the phone with another relative when her son attacked her.

“We talked to him and he confessed. He said, ‘You know, I have wanted to kill my mother for many, many years because she got on my nerves,’” Judd said. “We asked him, ‘What’s your relationship with your mother?’ and, he said about an eight out of 10, that he really loved her, but she irritated him.”

The mother was a second grade teacher and was loved by the community, Judd said.

“This is a horrible event,” Judd said. “It’s a very sad day with an inexplicable, vicious murder,” he said.

Jail records didn’t list an attorney for Espinoza.