The Dayton gunman fell under the sway of “violent ideologies” and had an “obsession” with mayhem before he killed nine people in the heinous shooting, authorities said Tuesday, as the investigation inched forward.

“We have found very specific violent ideologies that the shooter, we know, followed and was interested in,” said Todd Wickerham, special agent in charge of the FBI’s Cincinnati Field Office, of shooter Connor Betts.

Wickerham refused to elaborate on the exact nature of those ideologies, citing a need to let the investigation play out properly.

“It is absolutely critical that we do this investigation the right way,” he told reporters in an afternoon press briefing. “This community and our country deserve an answer as to why this happened.”

Wickerham did reiterate, however, that there is no evidence Betts was motivated by either race or the El Paso massacre, which happened about 13 hours before the Dayton rampage.

“Material 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,” added Dayton Police Chief Richard Biehl.

“While we do not have true clarity of the motive of the assailant, based upon evidence obtained, we do have a more developed picture of the evolving mindset of the assailant,” said Biehl.

Though both lawmen kept mum on the details of what led Betts, 24, to murder nine people — including his own sister — with an AR-15-style rifle early Sunday, signs of his disturbing preoccupations have emerged.

Those red flags include Betts boasting of his knowledge of mass shootings to an ex-girlfriend, and holding a gun to the head of a former friend months before the attack.