Anthony Lemus, 20, turned himself in on Monday and was booked on a murder charge, according to the Los Angeles Police Department. He is being held on $2 million bail.
Miguel Penaloza, 36, was working on July 15 when two people walked inside the store in the 4000 block of Eagle Rock Boulevard. Officers say Penaloza confronted the two as they tried to leave the store without paying.
There was a brief struggle before one of the suspects shot Penaloza. He died at the scene.
The LAPD did not provide any information on the second suspect, and it was unclear whether Lemus was the one who pulled the trigger.
Penaloza's family and friends have described the victim as a caring man who helped his coworkers out and was working to support his parents. He was also planning to leave the job soon and had already given his notice.
"Very loving. He always had a smile on his face," said coworker Lesly Garcia. "He always talked about his family, his parents. He lived with his parents and took care of his parents. He worked two jobs to support his parents."
A friend and former coworker said he did not feel safe while working at the store.
"I was the closing supervisor, and we always had people coming in -- stealing liquor and beer, beer runs and, unfortunately, at times there was only two of us," said David Cruz.
He and others say security is an issue at the store, and they hope something can be done to prevent more tragedies.