A 16-year-old high school student arrested on suspicion of killing a classmate and partially dismembering her body has told investigators she wanted to try dissection techniques on a human being after reading medical textbooks and practicing on a cat, police sources said on Wednesday.

The girl in Nagasaki Prefecture, who was arrested Sunday, also revealed she'd "had a desire to kill someone since middle school," the sources said.

Nagasaki police said they found several medical textbooks at the crime scene, an apartment in the city of Sasebo where the girl had been living alone.

The police will continue their investigation based on her statements and are now likely to order psychological tests.

The girl is under arrest for allegedly beating and strangling to death 15-year-old Aiwa Matsuo, for whom a funeral service was held in Sasebo on Tuesday.

Police also obtained several security camera recordings of the day of the killing from a shopping street near the apartment.

According to the police, the girl has said she and the victim went shopping together before the murder. They will now try to retrace the pair's activity by analyzing the security camera footage.