When [Latasha Harlins] entered Soon Ja Du's store in South Los Angeles, she was going to buy a bottle of orange juice. Du shot the teen-ager, after Du believed that Latasha was trying to steal the juice, Du's son said. A security camera videotape of the incident last Saturday reportedly shows otherwise. Police said the videotape corroborated witness accounts that Latasha had put the juice in her knapsack but was approaching the store counter with money in her hand. After a brief scuffle with Du, Latasha threw the orange juice on the counter and was heading out of the store when Du shot her in the back of the head, police said.