Authorities have not narrowed down the motive for the attack.

“It is our belief that it was totally unprovoked, whatever it was. We’re leaving no stone unturned. We’re going to leave every motive out there as a possibility,” Gonzalez said.

Authorities acknowledged that tracking down a killer on the vague description of a pickup truck will be a challenge in a sprawling metropolis teeming with similar vehicles.

“Yes, we know we’re in Texas. Yes, we know we have a lot of pickup trucks out there,” Gonzalez said. “But when you put the pieces together, consider that we’re looking for a bearded man, possibly in his 40s, driving a red pickup truck. This could be your neighbor. This could be your co-worker.”

He appealed for the public’s help, especially those with security cameras attached to their homes and businesses, to look for any sign of the man in the red truck.

And to the killer, should he be listening, Gonzalez had sharp words.

“I would suggest that you do the right thing and turn yourself in. There’s no need for anyone else to get harmed,” he said.