Police turned over to prosecutors Wednesday their case against a 21-year-old murder suspect who committed suicide on Feb. 5 shortly before he was to be arrested for the December slaying of a 7-year-old boy in a Kyoto elementary school playground.

Police said they took the action after analyzing the purported confession letters and memos indicating that Hiromasa Okamura, 21, fatally stabbed Toshiki Nakamura with a kitchen knife on the grounds of Hino Elementary School in Fushimi Ward on Dec. 21.

Police found a hammer, paint, a woolen cap, gloves and a note apparently written by Okamura saying he held a grudge against the school education system and claiming responsibility for the killing.

However, police said the suspect's suicide may prevent them from establishing a motive for the murder.