Police released the footage at a news conference on Wednesday. Investigators asked for the public's help to locate the person who killed Martha Sanchez.
The video shows the suspect walking along Broadway on the night of Sept. 17. He is described as a black male in his 30s, about 6 feet tall. He was wearing a long jacket, green on top and blue on the bottom, and a baseball cap.
The suspect is seen leaving the store after the murder and running away from the area. He was last seen running south on Broadway.
Authorities say the 39-year-old mother of five was shot twice at the Happy Bargain 99 Cent Store on the 7400 block of South Broadway. She was working alone at the time. Investigators say the suspect entered the store, robbed Sanchez and then shot her.
Sanchez was rushed to an area hospital, where she later died.
Some of Sanchez's family members attended Wednesday's news conference.
"Nothing is going to bring my sister back, the mother of my niece and my little nephew, and the pain that we are going through is really very hard. I don't wish this for nobody," said Juan Arevalo, Sanchez's brother.
LAPD Detective Eric Crosson said the suspect is believed to have been out and about for at least 30 minutes prior to the murder.
"There were people on the street that unknowingly walked right by him, and we're hoping that they'll come forward now that they know what we're actually looking for," said Crosson.
Police say they do have a person of interest in this murder who is in custody on an unrelated charge. Authorities are hoping to attain some information that would either tie him to the case or eliminate him as a suspect.
The city of Los Angeles is offering a $50,000 reward in the murder. If you have any information about this incident, you're urged to contact the LAPD's Gang Homicide Unit.