A Chinese immigrant pleaded guilty on Wednesday to slaughtering his cousin’s wife and four children with a meat cleaver while staying at their Brooklyn home two years ago.

Mingdong Chen, 27, was sentenced to 125 years in prison after he pleaded guilty to three counts of second-degree murder and two counts of first-degree manslaughter, according to The New York Times. He was originally charged with five counts of first-degree murder.

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“I only would have accepted this plea if never again under any circumstances could he be free in society,” Justice Vincent M. Del Guidice said.

Prosecutors said that Chen’s cousin’s wife, 37-year-old Qiao Zhen Li, called her mother-in-law in China on the evening of Oct. 27, 2013, to tell her that Chen was threatening the family with a knife.

The mother-in-law in turn called other relatives in New York to check on her, but when they arrived at the family’s home, they found Li and her four children dead and Chen covered in blood, the Associated Press reports.

According to police, each of the victims had been stabbed multiple times and had their throats slashed. It’s unclear what led to the deadly attack, but relatives said that Chen, who came to the United States in 2004, was jealous of his fellow Chinese immigrants’ success. After his arrest, Chen also told investigators, “everyone seems to be doing better than him,” The Times reports.

But to this day, he has never offered a specific motive for the rampage.