LOS ANGELES » Videos played Tuesday in the case of four teens charged in the murder of a Chinese graduate student showed the victim being surrounded by shadowy figures and then chased down the street.

Details were not sharp in the black and white surveillance video, but a prosecutor said later that they showed the beating that killed Xinran Ji.

A judge will determine if three of the teens, including two juveniles, will stand trial in the killing of Xinran Ji near the University of Southern California. A fourth suspect faces a later hearing.

Authorities allege Jonathan Del Carmen, 19; Andrew Garcia, 19; Alberto Ochoa, 17; and Alejandra Guerrero, 16, were trying to rob Ji, 24, when they beat him with a bat and wrench and left him for dead. Ji was able to make it to his apartment, where a roommate found him dead in bed in the morning.

Photos displayed at the hearing showed Ji lying in his bed in what appeared to be a blood-stained shirt and pants. Puddles, droplets and smears of what looked like blood were found throughout the apartment.

Los Angeles Detective Matthew Courtney said he and his partner followed a possible trail of blood from the apartment, down the street and around the corner.

The school and Los Angeles police beefed up patrols on and around campus after two Chinese graduate students were murdered outside an off-campus apartment in 2012. The university is surrounded by historically high-crime neighborhoods.

The July 24 killing of Ji renewed criticism about the safety of Chinese students at USC. China’s consulate general said it was concerned about student safety at the campus.

Until last year, USC had recruited the highest number of foreign students in the country for more than a dozen years. It dropped to No. 2 behind New York University, according to a survey by the Institute of International Education, though it remains very popular with students from abroad. About 40 percent of its foreign students are from China.

Ji enrolled at the university in 2013 after excelling at one of China’s best universities, where he won a prize for mathematical modeling.

Del Carmen and Garcia could face the death penalty if convicted. Ochoa and Guerrero are charged as adults but can only face up to life in prison without the possibility of parole if convicted because of their ages. All four are being held without bail.

Proceedings against Garcia were postponed because his lawyer was ill and questions were raised about his mental competency. Garcia blurted out obscenities in court Monday at the end of a brief hearing.