A man wanted by San Diego police in connection with a killing behind a popular gym in the Midway District is well-known as a boxing and mixed martial arts coach.
Ernesto Castellanos Martinez, 41, also uses the name Ernesto Castellanos according to San Diego Crimestoppers. The agency is offering $1,000 reward for information on Martinez' whereabouts following the Feb. 28 fatal shooting.
Martinez is known throughout the boxing and MMA community in San Diego where he has coached for years, according to one gym owner.
Alexander Mazin, 27, was shot to death behind the 24-Hour Fitness on Midway Drive and Kemper Street just before 11 a.m. Mazin was found by police on the ground, suffering from bullet wounds to his upper torso.
Monica Stepanof was at the gym and tried to help.
“I grabbed some towels at the front desk and ran to the back where I found the gentleman slumped over by his truck with a gunshot wound to his neck and his back and blood everywhere," Stepanof said.
Mazin was pronounced dead at the scene shortly after.
Martinez is described as the only suspect in the shooting by homicide detectives.
Martinez knew the victim but police won't elaborate on the relationship more than saying the connection was the mother of Martinez' children.
TRAFFIC ADVISORY: Our SWAT Team has been called out regarding a barricaded suspect in Mid City. Please avoid the areas of 3000 Upas and 3000 Ray Street. More info to follow. pic.twitter.com/kJvB0per4v— San Diego Police Department (@SanDiegoPD) February 25, 2018
NBC 7 contacted one local business where Martinez worked as an independent contractor several years ago.
Mike Liera with The Arena said some of the personal information his management staff had on Martinez did not match up with his record.
"When we asked him to produce verifiable information, he was unable to do so," Liera said. "Consequently, we ended our relationship with him."
Liera said Martinez went on to coach at several other gyms in San Diego.
The department is asking anyone with information regarding Martinez' location to contact the Homicide Unit at (619) 531-2293 or Crime Stoppers at (888) 580-8477.
Martinez is believed to be armed and dangerous. If he's spotted, police suggest calling 911.
Anyone aiding in hiding Martinez from police could face charges, officials said.