DALLAS (CBSDFW.COM/AP) — A federal law enforcement official says the FBI received a call three years ago about the 22-year-old man who opened fire on a courthouse in downtown Dallas.

Brian Isaack Clyde was shot and killed Monday by security officers at the Earle Cabell Federal Building.

Brian Clyde

There were no other serious injuries or deaths in the attack.

The official, who spoke on condition of anonymity because the investigation is ongoing, says a member of Clyde’s family called a national tip line to say he was suicidal and had a fascination with guns.

The official said the July 1, 2016 call from a family member expressed concern for Clyde but did not contain a specific threat and therefore the FBI did not investigate.

The call came while Clyde was enlisted in the U.S. Army.

Clyde’s stepmother, Heather Clyde, told CBS 11 on Wednesday, she had no idea he wanted to commit mass murder and thought perhaps he was trying to commit suicide.

Heather Clyde – Brian Clyde’s stepmother (Steve Pickett – CBS 11)

“It was so out of the blue,” said Heather Clyde. “Not near the surface of who Brian was to us.”

She said he was “lovable and quirky.”

Heather Clyde said she saw nothing, not in his social media posts or his interactions with them, that suggested he would try to shoot and kill people.

(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)