An 18-year-old Tokyo high school student has been arrested on suspicion of murdering his girlfriend, and he is also being interrogated about his involvement in a fire that burned her corpse and her apartment, police and investigative sources said Monday.

The teenager, whose name is being withheld because he is a minor, admitted to strangling Mai Sato, 17, they said, adding that he had been turned over to prosecutors in the morning for further investigation. He was arrested Saturday.

Police alleged that the suspect assaulted the girl, who went to the same school, at her apartment in Tokyo's Taito Ward or somewhere nearby between around 8:30 p.m. on May 3, when he left the apartment, and 8:35 a.m. the following day, when he returned. The fire began at around 8:30 a.m. on May 4.