To help catch him, the city of Lancaster is offering a $5,000 reward for information leading to an arrest or conviction of the suspect or suspects.
Peatry was gunned down just after 1 a.m. Sept. 5. She was shot after a fight that broke out at a birthday party she attended on the 400 block of Sixth Street in Lancaster.
Peatry was killed, six others were wounded. Some of those wounded were no older than Peatry.
"I just don't understand. This is the fifth day of October and this happened in September, it's thirty days," said Peatry's father, Marquise. "Just please do the right thing and get these guys off the street."
"Dominique was our baby and they took her life," said the teen's grandmother, Jacqueline. "I don't understand it but I'm asking anyone who was at the party, please, I don't care how small it is to please either call the detectives or the tip line."
Despite there being a room full of people at the party, the case remains unsolved.
"What I've been truly shocked by has been the communities lack of cooperation in this terrible murder investigation," said Capt. Alex Anderson of the Los Angeles County Sheriff's Department. "There were in fact witnessed at that party and they need to do the right thing and come forward."
"I do know that the people who were at the party, they know who those cowards are," Jacqueline Peatry said. "I'm asking you to please help us. Please, we miss her so much."
Anyone with information is urged to call detectives anonymously at (323) 890-5500.