A Texas man brutally stomped and beat his coworker to death over a misplaced set of car keys. He was convicted of murder Wednesday.

41-year-old Martin Gutierrez Jr. was convicted by a Dallas jury for the 2015 incident that occurred in a motel and resulted in the death of Cesar Martinez-Zamarripa. He’d pleaded not guilty.

He’s said to have attacked Mr. Martinez-Zamarripa on May 31st at a Deluxe Inn in Carrollton, Texas after the two men argued over a set of lost keys.

The two of them had visited Pandora’s Men’s Club with two other men that night, and as the four of them leftt, Gutierrez couldn’t find his keys. He accused Martinez-Zamarripa of being the one who lost them.

The men ended up having to hail a cab to the motel they were staying at while their construction job had them in Dallas, and Gutierrez and Martinez-Zamarripa continued their heated argument about the lost keys.

As they got closer to their rooms, the argument turned physical, and the two exchanged blows.

Gutierrez eventually knocked Martinez-Zamarripa to the ground, then began kicking and stomping on him. The attack lasted for approximately 15 minutes.

Police found the perpetrator hunched over the victim’s body inside one of the motel’s rooms. He was sitting on the edge of a bed, his foot resting on the victim’s neck. His shoes were covered in blood.

“I killed him,” Gutierrez told officers. “I stomped him.”

He’s now facing up to life in prison.