The gunman killed nine people in Dayton, including his sister, before he was slain by police.
An FBI official said he had a history of violent obsessions and previously mused about committing mass murder.
Following the mass shooting, the parents of suspect Connor Betts and his sister Megan said they weren't ready to speak and asked for privacy for themselves and their neighbors.
Bellbrook Chief of Police Doug Doherty read a statement from the family on Tuesday (August 6).
"The Betts family is shocked and devastated by the events of Sunday morning in the Oregon District," he said.
"They offer their most heartfelt prayers and condolences to all of the victims, their families and friends." Police said in the initial aftermath of Sunday (August 4) morning's bloodshed they believed the slain suspect had acted alone.