"He was a good person. He was a good friend," Jake Hunt said of Micah Johnson. "All I see is Micah from high school."
Johnson, 25, was the lone shooter in the Thursday night attack that left five cops dead, police say. Johnson later died during a standoff when police detonated a bomb delivered by robot.
His old friend from John Horn High School in Mesquite, Texas, said Johnson never showed problems of anger.
He was "really funny," Hunt said of the 2009 graduate. "You couldn't go a day without him making you laugh at least twice a day."
Hunt, who now lives in Forney, Texas, described their mutual high school friends as "like the outcast" group at high school, all with different interests. Johnson was in ROTC.
"We were tight within our group," Hunt said. "He [Johnson] just didn't socialize with everyone [outside the group.]"
After high school, Johnson trained and served in the U.S. Army Reserve as a carpentry and masonry specialist, defense officials said. Johnson, a private first class, was deployed to Afghanistan from November 2013 to July 2014, according to his service record. He served as an Army reservist until April 2015.
They kept in touch when Johnson returned from the military and Johnson would show off the wrestling moves he had learned, Hunt said.
"He seemed so happy" at that time, he added.
Hunt said he was shocked and hurt to learn of last week's shooting. "I didn't think he would do something like that ... we couldn't believe it was real," he said.
"I have shed a few tears for him," he said. "I'm never going to get to see my friend again."
The suspect said he wanted to kill white people, especially white police officers, Brown said.
Police said Johnson had bomb-making materials, ballistic vests and rifles in his house. Detectives were also analyzing information in a "personal journal of combat tactics" they recovered, police said.
Dallas police said Johnson had no criminal history.
ABC News' Matt Gutman, Stephanie Wash and Robert Zepeda contributed to this report.