It was an exceptionally messy crime scene. 30-year-old Vincent Lei was face down in the entryway, his body covered in blood. His parents, mother Wan Yi Xu and father Hua Shun Lei, were found beaten to death in the garage. Lei’s wife Chia Huei Chu was in the in-law unit, and his sister Ying Xue “Jess” Lei was upstairs. The house was a disaster — pipes had been removed from sinks and the place was full of water. Windex, shampoo, white paint, and powder were scattered everywhere. And the bodies each had multiple signs of impact, presumed to have been inflicted by both ends of a claw hammer.

It was 2012, and the city has not seen a mass homicide with this many casualties since. The crime scene produced hundreds of pieces of evidence — including blood, DNA, and fingerprints — that tied the case to Binh Thai Luc, a friend of Lei’s. When the San Francisco Police Department caught up with him a day after the homicides, he was holed up in a San Mateo motel, reading about the case on a public computer in the lobby.

In October, more than five years after the murder, he went to trial. Today, the verdict was released, after the six women and six men in the jury deliberated for 7 days.

Luc was found guilty on all five counts of first-degree murder. His sentence will be announced at a later date.

During the five weeks that the defense and prosecution presented evidence and interviewed witnesses, a motive — which was missing in opening statements — slowly began to be revealed. Luc was known to friends to be a serial gambler. Despite having a good union job as a plumber, where he was paid $45 an hour, he would immediately withdraw all of his paycheck in cash as soon as it was deposited, presumably to take to casinos.

The day of the murder, Luc only had $1 in his bank account. He went gambling at Artichoke Joe’s Casino in San Bruno, where he lost. The pressure was on — his family had been served 7-day eviction notice, and he needed money fast.

It appears that Lei was dabbling in something illegal. In his in-law unit, authorities found a box filled with medical marijuana letters. He had $2,000 in cash in a jacket pocket in the closet. Cash seemed to have been stashed in several areas around the house.

And Luc may have known this. Despite having lost his money gambling at Artichoke Joe’s, and with only $1 in his bank account, he managed to give his mother $1,000 for rent the day of the homicides — a piece of evidence, Prosecutor Eric Fleming claims, that he took money from Lei’s home. When police arrested him in San Mateo, he had $6,500 in cash on his person.

“I don’t have to prove a motive, but I did just prove a motive,” Fleming told the jury during final arguments.

Motive aside, the evidence was just too damning. Lei’s blood was found on jeans at Luc’s house and in Luc’s car. Luc’s fingerprints were on a Windex bottle at the home on Howth Street, which was used to cover up evidence of the crime. And his skill as a plumber was displayed proudly for police to see, with the disassembled sinks that then flooded the place.

“This case was incredibly unordinary,” said District Attorney George Gascón after the verdict was announced. “A case like this is very impacting on everyone — it’s impacting on the family obviously, but also impacting on the neighbors and everybody else.”

The end of the trial closes the door on a particularly dark and violent series of murders. But the story isn’t completely over: Defense attorney Mark Goldrosen told reporters he would be filing an appeal.

This is a breaking news story. Updates will be posted as information becomes available.

Want more details? Our last story on the case can be found here.