An autopsy report for Stephen Paddock revealed nothing new about what might have driven him to open fire on a Las Vegas country music festival in October, killing 58 people and injuring more than 850 others.

Toxicology tests showed Paddock’s system contained anti-anxiety medication – specifically, levels of benzodiazepines consistent with the drug Valium – but that he was not under the influence of them, since the substances were found in his urine and not in his blood, according to the Las Vegas Review-Journal. Benzodiazepines are sedatives typically prescribed to help treat anxiety and insomnia.

Paddock’s toxicology report also showed small amounts of lead, arsenic, antimony and selenium found in Paddock’s blood, but not at levels that would have caused violent or aggressive behavior, the newspaper reported.

“It seems that based on the autopsy reports there were no physical excuses for what Steve did,” Paddock’s younger brother, Eric Paddock, told the newspaper. “We may never understand why Steve did this.”

Paddock’s autopsy report was released Friday to The Associated Press and the Las Vegas Review-Journal, who had filed a lawsuit to obtain the results.

The autopsy included a separate examination of Paddock’s brain, conducted at Stanford University, which also found nothing unusual, according to The Associated Press.

In fact, other than having high blood pressure and bad teeth, Paddock was “a sober, healthy 64-year-old,” the AP reported.

Paddock’s autopsy occurred on Oct. 6, five days after the massacre, according to a preliminary report on the investigation released last month by the Clark County Sheriff’s Office. Las Vegas police detectives, along with FBI evidence team members, were there for the procedure at the Clark County Office of the Coroner/Medical Examiner.

What investigators still couldn’t answer was why Paddock, a man with no criminal history, enacted the worst mass shooting in modern U.S. history.