Further disturbing details began to trickle out about Trey Sesler, the Waller man accused of killing his parents and brother with a high-powered rifle.

During an eight-hour interview with Texas Rangers, Sesler confessed to killing his family and planning a Columbine-style attack on Waller High School, his alma mater, Waller Police Chief Phil Rehak and Waller County Sheriff Glenn Smith said at a joint press conference on the case Thursday morning.

A portrait of a troubled young man is emerging. Sesler, 22, told authorities he was a “loner” and said that over the past few years he set fires, shot at businesses in the middle of the night, and has killed livestock and his own pets, Rehak and Smith said. (With that knowledge, a video posted on his Facebook page about his missing pet rabbit takes on a sinister light.) 

“He further admitted to investigators that he studied serial killers to the point of grading their work and researched mass shootings,” Rehak said. “He had thoughts of committing acts of public violence such as these.”

Sesler is being held in Waller County Jail—where he is on suicide watch—in lieu of $5 million bond, Smith said.

Sesler attended Blinn College in Brenham and had almost two years of credit, Smith said. But he lived at home without a stable job, which led him to butt heads with his father. He seemed to find some escape on YouTube, where he called himself “Mr. Anime” and had posted 323 videos over the past five and a half years—mostly anime reviews—that amassed over a million views. (Read TEXAS MONTHLY‘s Michael Hall’s take on Sesler’s YouTube videos.)

KHOU had previously reported that investigators said Sesler killed his family “because he didn’t want them to be ashamed of what he was about to do.” But Sheriff Smith said that Sesler changed his story multiple times during his interview.

Investigators are combing through computers seized from his house and car as well as his handwritten journal to gather clues about Sesler’s possible motive. They are also interviewing his friends and trying to track down “everyone he’s ever played videogames with” in an effort to glean if anyone may have been working with him, Smith said.

Sesler has spent “a massive amount of time of studying violence and acting it out,” Smith said. But it remains unclear how close Sesler was to carrying out a mass shooting. But it appears he may have had the tools to carry one out: authorities raided a house in Hempstead yesterday where Sesler had stayed in the past and seized a half dozen weapons and “ammunition of various calibers,” Rehak said.

The Houston Chronicle‘s Linday Wise and Anita Hassan reported that the Sesler family home had been ransacked. “[A]uthorities also found remorseful words written on the walls in black marker that appeared to come from Sesler,” including “I love my family.”