The 24-year-old man who killed nine people in downtown Dayton, Ohio, was obsessed with violence, including other mass shootings, authorities said on Tuesday.
"The materials reviewed thus far reveal that the individual had a history of obsession with violent ideations to include mass shootings, and had expressed a desire to commit a mass shooting," Dayton Police Chief Richard Biehl told reporters.
The FBI is now taking the lead in investigating what may have motivated Connor Betts to open fire on crowds of people enjoying the nightlife of Dayton's Oregon District just after 1 a.m. on Sunday. One of the people he killed was his 22-year-old sister, whom he had driven with to Dayton earlier in the evening.
The development comes after the FBI also announced it is investigating deadly mass shootings in Gilroy, California, and El Paso, Texas, as domestic terrorism. In Dayton, investigators have yet to determine if Betts was motivated by a particular ideology, but evidence has so far revealed that he was seeking out information that promoted violence, FBI Special Agent in Charge Todd Wickerham said.
"We have found very specific violent ideologies that the shooter we know followed and was interested in," he said.
In addition to whether he was motivated by ideology, Wickerham said investigators will focus on whether any other person or group helped Betts or knew he was planning an attack. Investigators are also trying to determine why the gunman attacked the Oregon District.
"This community and our country deserves an answer as to why this happened," Wickerham said.
Wickerham added the investigation is in its early stages, and the FBI has much more evidence, including digital materials, to sort through.
Meanwhile, Betts' family issued a written statement Tuesday that was read by Bellbrook Police Chief Doug Doherty.
"The Betts family is shocked and devastated by the events of Sunday morning in the Oregon district," Doherty said. "They offer their most heart-felt prayers and condolences to all the victims, their families and friends."
The family also thanked officials for their "quick response to minimize casualties."
"They ask that everyone respect the family's privacy in order to mourn the loss of their son and daughter and to process the horror of Sunday's events," Doherty said.
Investigators have not found evidence that the Dayton attack was racially motivated or otherwise influenced by the shooting just hours earlier in El Paso, Texas, where a suspected gunman killed 22 people after publishing a white supremacist and anti-immigrant manifesto.
Betts had a history of making threats, particularly against women. A former high school classmate told BuzzFeed News he made a hit list, naming mostly girls in their school. Discovery of the hit list led to Betts's suspension, though he later returned to class.
More recently, he was the lead singer of a "pornogrind" metal band, BuzzFeed News revealed. Other musicians in the scene said while their lyrics are obscene and include themed sexual violence, they did not condone actually harming people and were disgusted by Betts.
Earlier this year, Betts showed a video of the Pittsburgh synagogue shooting to a woman on a first date. Adelia Johnson said in a statement to the Associated Press that Betts joked about having dark thoughts and had told her he had mental illnesses including bipolar disorder.
They dated for several months and she attributed his talk to mental illness, she told the AP. She added they broke up after what she described as uncontrollable urges, a red flag, which she also brought up to his mother.
“When he started joking about his dark thoughts, I understood,” she told the news agency. “Dark thoughts for someone with a mental illness are just a symptom that we have to learn how to manage.”