A Chinese graduate student has been charged with the murder earlier this month of a Chinese woman who harbored his former girlfriend after they broke up.

Chen Shifeng, 25, has been in custody for allegedly threatening his ex-girlfriend, who was not named. He is suspected of fatally stabbing Jiang Ge, a 24-year-old Chinese student, outside her second-floor apartment unit in Nakano Ward, Tokyo, on Nov. 2, the police said.

Chen and his ex-girlfriend attended the same graduate school and were living together between June and August, the police said. After they broke up, the girl, also 24, went to stay with Jiang, a mutual friend from their Japanese-language school.

Around midnight on Nov. 2, Chen allegedly stabbed Jiang in the neck with a knife in the second-floor hallway of her apartment building, the police said.

A surveillance camera captured Chen walking around the apartment building at the time of the murder, and he was also spotted near his ex-girlfriend's workplace earlier in the day, the police said.

Chen has remained silent about the allegations, the police said.

Police first arrested Chen on Nov. 7 on suspicion of sending a threatening e-mail to his ex-girlfriend on Nov. 2, and prosecutors indicted him on that charge on Thursday.