Dayton Police Chief Richard Biehl told reporters at a news conference that 24-year-old Connor Betts, who was armed with a .223-caliber rifle, had a gun that was modified in a way he felt was “fundamentally problematic.”

Biehl also added that if all of the magazines that Betts had were full  — which has yet to be confirmed as police have not had a chance to examine them fully — he would have had a max of 250 rounds, not excluding loose rounds found on the ground near him as well as in a backpack the 24-year-old was carrying at the time. Investigators have so far recovered at least 41 spent shell casings that are believed to have been from Betts.

“You can well understand in a very dynamic and chaotic scene as this was, with people running through the crime scene, with first responders running through the crime scene, with EMS traveling through the crime scene, evidence can be lost,” the police chief told reporters.

Adding shell casings that was recovered from Betts’ weapon, investigators have collected 48 45-caliber casings, 16 .233 casings and one shotgun shell casing that are believed to have been fired from the weapons of the six police officers who “neutralized” the gunman within 30 seconds after the first of “dozens of rounds.”

The police chief said that it’s not known if Betts solely targeted any of his victims in the popular entertainment district early Sunday. However, found it very hard to believe he didn’t recognize his sister, 22-year-old Megan Betts, when he opened fire and killed her and eight others.

“It seems to just defy believability he would shoot his own sister, but it’s also hard to believe that he didn’t recognize it was his sister, so we just don’t know,” Biehl said.

While the gunman was white and six of the nine killed were black, police said the quickness of the rampage made any discrimination factor in the shooting seem unlikely.