Christopher Canon, of San Francisco, was 15 when he shot 18-year-old Michael Price Jr., of Oakland, at the Metreon at Fourth and Mission streets on Nov. 11, 2007. He was arrested nearby after the shooting.
According to prosecutors, Canon was upset that Price wasn't moving fast enough down an escalator outside a video arcade at the complex.
Canon twice confronted Price, motioning to a gun he had hidden on him and threatening to "pop" him, prosecutors said.
Canon's attorney claimed Canon shot Price in self-defense after Price offered to fistfight him outside the mall.
San Francisco Superior Court Judge Anne-Christine Massullo discharged the jury this morning after they split, seven in favor of first-degree murder and five in favor of second-degree murder.
The jury had deliberated for nearly a week following the month-long trial.
Prosecutors said this morning that they intend to retry Canon, but that a decision had not yet been formalized.
Canon, now 18, remains in custody.