Two men were charged Tuesday over the killings of two Chinese graduate students that shocked Los Angeles last month, officials said.

Bryan Barnes, 20, and Javier Bolden, 19, could face the death penalty after being indicted on capital murder charges over the killings of engineering students Ming Qu and Ying Wu, both 23. They were arrested last week.

Neither of the suspects had criminal records, but they were also charged with attempted murder for incidents in December and February. Shell casings found at those scenes allegedly tied the pair to the students' killings.

The two Chinese students from the University of Southern California (USC) were shot in the early hours of April 11, as they sat in a car in an area southwest of downtown LA.

Their suspected killers were detained last Friday in separate operations in south LA and Palmdale, north of the city, by teams including the LA Police Department and the Federal Bureau of Investigation.

"The special circumstances of multiple murders and murder during commission of a robbery makes the two defendants eligible for the death penalty," the LA County District Attorney's Office said in a statement.

"Prosecutors will decide later whether to seek the death penalty against Barnes and Bolden."

Both suspects were also charged with attempted murder for allegedly shooting a 20-year-old man during a December 3 party in South Los Angeles. Barnes was also charged with an attempted murder on February 12.

"Los Angeles Police, who investigated the case, said shell casings allegedly tied the suspects to both the USC fatal shootings and the earlier attempted murders," the district attorney's office said.

The parents of the victims filed a wrongful-death lawsuit against the USC last week.

They noted that the school "actively solicits international students, particularly from China, for its graduate studies program for which it receives a substantial sum of money from tuition to help fund the university."

The school's website states the university "is ranked among the safest of US universities and colleges, with one of the most comprehensive, proactive campus and community safety programs in the nation," they added.