James Beach, also known as James Michael Garcia, was arrested Sunday and is facing a murder charge in the death of 45-year-old La Puente resident Luis Campos.
Campos joined his three brothers in Sin City on April 30 for a bachelor party. He was set to be the best man in his brother's wedding.
Campos and his younger brother were in line for the Vanguard, a bar on Fremont Street, when they were approached by two men around 1:34 a.m. The attacker asked what Campos was looking at and punched him.
The punch was so severe it knocked Campos out and caused brain bleeding. Paramedics rushed him to the hospital, but he never regained consciousness and died Thursday at a Las Vegas hospital.
The suspects fled and were captured on surveillance video down the street from the crime. There was no word on whether the second suspect has been found.
The close-knit family said they're planning a funeral all because of one man's unprovoked brutality.
"These guys knew what they were doing. They knew they were going to sucker punch him. They knew they weren't going to sit here and give him a fair break. It was the act of a coward - two cowards," Campos' brother Adam Garibay said.