The incident occurred outside the Shores apartment complex on the 4200 block of Via Marina Court just before 2:45 a.m.
"Deputies discovered an adult African-American male suffering from gunshot wounds. He was subsequently pronounced dead at the scene," said Los Angeles County Sheriff's Lt. Dave Dolson.
The sheriff's department identified the victim as 47-year-old Patrick Odoikyene.
"Our investigation leads us to a possible suspect: a male black adult dressed in dark clothing, wearing a dark hooded sweatshirt that may or may not have a logo or an emblem on it," said Dolson.
Homicide Bureau detectives were handling the investigation, and say a murder in this area is very unusual. The city is a top attraction for both locals and tourists, and hosts several inns and hotels.
The homicide was believed to be the first in the waterfront community since 2007.
Neighbors were stunned to learn of the shooting in this usually low-crime area. One man couldn't move his car because it was part of the crime scene.
"I was very surprised. I saw the police officers and I said 'is it safe to go and walk the dog?' so yes we're very surprised," said Lynn Reynolds of Marina Del Rey, who moved into the building last week. "We have a 16-year-old son, and he walks quite often here, you know, late at night, walking the dog on his own. We're new to L.A., and it's kind of a different ballgame."
"Anya" lives just above where the shooting happened and says she was in bed when she heard two men arguing.
"I just heard somebody arguing, and there were some loud noises," she said.
Reynolds couldn't believe she and her family knew the victim.
"He was really nice, took a personal interest in you, jovial outgoing personality," said Reynolds. "I do not know what his family life was like, but odds are he had family, and it's the holiday season, and it's a real tragedy."
One person told investigators they saw the suspect flee the scene, and described him as an African-American male, wearing a dark-colored hooded sweatshirt.
The investigation is ongoing. Anyone with information regarding the incident was urged to call Crime Stoppers at (800) 222-TIPS.