An illegal alien from Vietnam was convicted on Monday of bludgeoning a Chinese immigrant family of five with a hammer after a prior violent crime and failed deportation attempt.

Prosecutors called the brutal massacre among the worst mass homicides in San Francisco’s modern history, according to the San Francisco Chronicle.

Binh Thai Luc was slated for deportation in 2006, but while in the U.S. in 2012, he murdered five members of the Lei family. Luc has a violent criminal history, according to Fox News.

District Attorney George Gascón called the crime “a very gruesome, brutal murder” in comments to the Chronicle. On March 23, 2012, Luc robbed the family’s home as well as committed the brutal murders.

A San Francisco Superior Court jury on Monday found him guilty on five counts of murder. The five members of the family murdered were 65-year-old Hua Shun Lei, his wife Wan Yi Wu, 62, their daughter Ying Xue Lei, 37, their son Vincent Lei, 32, and Vincent’s wife Chia Huei Chu, 30.

A 12-year-old niece of Vincent Lei found the bloodied bodies and ran out of the home screaming for her mother, according to the Chronicle. The bodies had been covered in bleach and other cleaning products, and the home was flooded after the killer ran faucets and detached pipes.

In 1998, Luc was convicted of armed robbery of a Chinese restaurant and assault with a deadly weapon, according to the Fox News report. He served eight years in California’s San Quentin State Prison. Luc was then given over to immigration officials for deportation, but his home country of Vietnam refused to provide travel documents. He was released in 2006, and the Chronicle noted that this was in accordance with federal law.

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