Suspect arrested in cold-case murder of Texas family, alleged killer upset over failed job promotion

Police arrested 58-year-old Feng Lu for the 2014 murder of a Texas family of four on Sunday. The court filings theorized that Lu allegedly committed the killings because he was upset about not receiving a job promotion, KTRK-TV reported.

In 2014, Maoye Sun and Mei Xie were shot and killed in their Cypress home, along with their two sons, 9-year-old Timothy and 7-year-old Titus. While authorities strongly suspected Feng Lu, they could not place him at the scene of the crime. As a result, leads ran dry for more than eight years.

Authorities believed that the family of four was attacked in their home on Friday, January 24, 2014. Their bodies were not discovered until Monday after Maoye Sun failed to show up to work.

Feng Lu, Maoye Sun's coworker, became a suspect early on in the case because he had purchased a firearm the day before the shooting. Police believed that the gun was the same weapon used in the murders.

New court documents disclosed Lu's possible motive for committing the murders. Investigators believed that he was disgruntled about not receiving a job promotion.

Lu told police that he had asked his coworker, Maoye Sun, to recommend him for a promotion. He reported hearing a rumor that Sun did not put in the recommendation. He called Sun to ask about it, and Sun informed him that he did recommend Lu.

The suspect told police that when he arrived at work the next day, he thought he was being "treated differently" by his coworkers. Lu assumed Sun had told coworkers about the phone call and talked badly about him. He blamed Sun because he did not receive the promotion.

Lu insisted that he did not know any other members of the Sun family or where they resided. Because authorities could not prove that Lu was inside the Sun home, family and friends remained unaware that he was a suspect.

Court documents revealed that new technology was able to place Lu at the scene. This year, investigators retested an old purse found inside the home using STRmix software. The software identified Lu's DNA by separating DNA strands from multiple individuals found on the purse.

With this new evidence, police had enough to issue a warrant for his arrest.

Feng Lu was arrested in San Francisco on Sunday after returning from a trip to China. He is currently being held in San Mateo County Jail and awaiting extradition to Texas. Lu is charged with capital murder for the deaths of the Sun family.