CNN  — 

When family members of 19-year-old Orlando Harris grew concerned about his mental health, they seemed to do everything right, the St. Louis police commissioner said.

“They contacted us, said that he had a firearm,” Commissioner Michael Sack said Wednesday.

“The mother at the time wanted it out of the house,” he said. “The officers, in their response, handed it over to somebody else, an adult who was lawfully able to possess it.”

At times, the teen’s family also committed him to a mental institution, Sack said.

Yet somehow, Harris managed to get access to an AR-15-style rifle and 600 rounds of ammo. And on Monday, he took his deadly arsenal to Central Visual and Performing Arts High School and wreaked terror on his alma mater.

By the end of the rampage, a talented student and a heroic teacher were dead. Harris was killed by officers.

And community members are stunned as to why the proactive interventions described by police didn’t seem to work.

‘They made every effort’

In addition to removing Harris’ firearm from the house and getting mental health treatment for the teen, the gunman’s family took additional steps to help prevent trouble.

“They would search his room on occasion because they were concerned,” the police commissioner said. “They were constantly in touch with the medical providers who were providing medical care for him.”

Harris’ family also had a system to track the items he received in the mail and monitored his interactions with others to try to ensure he was engaging with people and felt loved, Sack said.

“I’ve got to give credit to the family,” the police chief said. “They made every effort that they felt that they reasonably could. And I think that’s why the mother is so heartbroken over the families that paid for his episode.”

More details emerge from a revealing note

After the gunman forced his way into the school and opened fire, investigators found a notebook and a handwritten note left in the car he drove, Sack said.

“I don’t have any friends. I don’t have any family. I’ve never had a girlfriend. I’ve never had a social life. I’ve been an isolated loner my entire life,” the note said, according to Sack. “This was the perfect storm for a mass shooter.”