A Chinese man who murdered a mother and her four children in New York was sentenced to 125 years to life in prison Tuesday.

On Oct. 27, 2013, 27-year old Mingdong Chen was staying with family in a Brooklyn apartment when he picked up a meat cleaver and killed his cousin's wife Qiao Zhen Li, 37, and her two daughters (ages 9 and 7) and two sons (ages 5 and 1), who were found with stab wounds to the head and neck, according to Agence France-Presse.

"This defendant's vicious and sadistic attack makes him completely unfit to remain in society, and he will now spend the rest of his life behind bars. While we will never know what drove him to commit these murders, I hope that this sentence will offer this grieving family some measure of comfort," said Brooklyn District attorney Ken Thompson, according to AM New York.

There is no definitive reason why Chen killed his relatives since he has not yet disclosed it to the police. Authorities speculate he was jealous of the success of his family members since he had been in the United States for 10 years but was still struggling.

"He made a very soft comment that since he came to this country, everybody seems to be doing better than him," said former NYPD Chief of Department Philip Banks III, according to the Inquisitr.