Officers responded at 12:05 a.m. Tuesday to a report of a battery that had occurred in the 2700 block of Main Street, near Jameson's Pub, the Santa Monica Police Department said in a news release.
"A fight ensued on the street when the Jameson's manager asked several patrons to leave," the statement said. "Out on the street, one of the patrons punched the manager, causing him to lose consciousness."
The manager was not breathing when the officers arrived at the scene, according to police. The officers performed CPR until firefighter-paramedics from the Santa Monica Fire Department arrived and took over.
The injured man was transported to a hospital, where he died, authorities said. His name was not immediately released.
All three patrons involved in the incident were initially arrested and booked at the Santa Monica Jail, the news release said.
After an investigation, the person responsible for punching the victim was identified as 26-year-old Leonard Hector Korpie, a resident of Venice, the Police Department said.
On Thursday, the Los Angeles County district attorney's office filed a homicide charge against Korpie, who was being held on $2 million bail, the statement said.
Police did not release the names of the other two suspects, or information about what charges, if any, they could face.
Anyone with information about the incident is urged to contact police Detective Hector Tavera via email at Hector.Tavera@santamonica.gov. Tipsters may also call the watch commander at (310) 458-8427.
City News Service contributed to this report.