Additional witnesses took the stand Tuesday at the Los Angeles Superior Court in the murder trial of an 18-year-old woman accused in the beating death of a USC graduate student from China.

Alejandra Guerrero is the first of four suspects charged in connection with the July 2014 murder of Xinran Ji. Guerrero, who was 16 at the time of the murder, is now being prosecuted as an adult. If convicted, she faces life in prison without parole.

On July 24, 2014, Ji, an electrical engineering student, was walking back from a study group around 12:45 a.m. when he was beaten near the corner of 29th Street and Orchard Avenue, according to the L.A. County District Attorney. He made it back to his apartment after the attack, but his body was found around 7:00 a.m. by his roommate, prosecutors said.

Guerrero, along with the others accused, was charged with one count of murder with the special circumstance of murder during an attempted robbery. She was also charged with one count of robbery, attempted robbery, and assault with a deadly weapon in a second attack on a man and a woman at Dockweiler Beach following the USC-area beating.

Guerrero's co-defendants — Jonathan Del Carmen, 21, Andrew Garcia, 20, and Alberto Ochoa, 19 — are awaiting trial in connection with Ji's killing. Garcia and Ochoa are also charged with robbery, attempted robbery and assault with a deadly weapon involving the alleged attack at Dockweiler Beach.

Last week, jury selection wrapped up and opening statements were held before witnesses were called to the stand Friday. Two former USC students, one of Ji's study partners and his roommate, as well as two police detectives testified before the jury, according to the Ji family's lawyer, Rose W. Tsai.

"For the past two plus years, everyday has been agonizing to the Ji family…They go day-by-day living in hope of seeing the justice being done of this case," Tsai said.

In court Tuesday, LAPD detective Matthew Courtney played footage of the initial contact between the four suspects and the victim.

The first video shows passengers getting out of a car, someone coming into the frame of the camera, unclear activity, and then someone running from the scene. The detective identified the four passengers as Del Carmen, Garcia, Ochoa and Guerrero. The man running from the scene was identified to be Ji.

The second video shown by the detective shows Ji running again with Carmen and Garcia chasing him.

In response to the footage, attorneys for defendant Guerrero noted that there was a fifth female in the vehicle, who is under investigation and whose name has not been released.

Other witnesses included the USC Department of Public Safety (DPS) security systems administrator and Andrew Koh, the Chief of Operations of Security Footage at USC, who worked with LAPD to extract footage from surveillance cameras the night of the attack.

The individuals were questioned about USC surveillance procedures and asked who else worked with the camera footage of the incident.

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