CYPRESS, Texas (KTRK) -- The man charged in the murders of a family of four in the Cypress area was upset about a job promotion that didn't happen. That's the motive revealed in court filings in the Sun family murder that went unsolved for eight years.
For years, there were no new leads in the January 2014 massacre that led to the shooting deaths of two parents - father, Maoye Sun and his wife, Mei Xie - and their two small children - 9-year-old Timothy and 7-year-old Titus.
"It was gut-wrenching," Jamie McLain said, whose two boys were the same age as the Sun boys and growing up together. "From the time they were young. They played soccer together, did Cub Scouts together. We were all in the same Dens."
This past Sunday -- more than eight years after the Sun family was killed -- 58-year-old Feng Lu was arrested in California and charged with capital murder in connection with their deaths.
New court documents reveal that all of this may have started because of a work issue. During an interview with investigators, Lu told police he asked Sun for a recommendation for a promotion.
Lu told police he heard that Sun did not provide the recommendation, so he called him to ask why he didn't give it. Sun reportedly told Lu he did recommend him, the documents state.
When Lu returned to work the next day, he told police he felt he was being "treated differently" by his coworkers. He said he thought Sun said something derogatory about him to his coworkers after their phone call, and that's why he wasn't selected for the promotion.
According to court documents, Lu bought a gun on Jan. 23, 2014. Investigators believe he used that same gun to kill the Sun family two days later.
Investigators believe the Suns were shot in their Coles Crossing home sometime on Friday, Jan. 24, 2014. Their bodies weren't discovered until the father failed to show up to work the following Monday.
Lu told investigators he didn't know the rest of the Sun family, or where they lived. However, court documents say DNA evidence contradicts that statement.
Friends and neighbors had no idea Lu was even a suspect for eight years.
"I talked to this psychologist, and he said, 'You may never find out, what happens for your lifetime,'" Jei Zhang, a friend of the Suns who also had kids the same age, said. "Our kids played piano together. It was so sad."
Even though investigators had the gun evidence and collected DNA, they could not put Lu inside the Sun's home. Then, earlier in 2022, they tested an old purse found inside the home again. This time, they used a new DNA software called STRmix. Developed in New Zealand over the past decade, this software can separate DNA strands of multiple people found at crime scenes.
The new software gave investigators a hit, Lu. Now, all of the pieces from the past eight years fell in place. Investigators finally had enough for a warrant, and Lu was arrested.
McLain hopes the community can begin to heal.
"I think relief and maybe justice will be served. This was two precious boys in our community, that had bright futures, and it's not fair that they were gone. I think it's time for justice," McLain said.
Lu was arrested on Sunday in the San Francisco Bay Area as he arrived back in the states from China. He is currently in the San Mateo County Jail -- awaiting extradition back to Texas.