Police revealed Saturday that an 18-year-old boy was wrongly jailed for 16 days on suspicion he sexually abused a 14-year-old boy last month in Urawa, Saitama Prefecture.
The Urawa Nishi Police Station released the teenager on Thursday, after another suspect, Yoshiharu Kakumoto, 20, confessed to the crime, they said.
Kakumoto has been taken into custody and reportedly admitted he engaged in an obscene act with the boy on Feb. 3.
Police said, "We depended too much on the testimony of the victim, and communicating details of the investigation did not go properly between sections within the station."
The incident occurred when the boy, a third-year junior high school student from Yono in the prefecture, was on his way home from cram school.
The student and his mother went to the boy's school the following day and told a teacher that the offender was either the 18-year-old man or Kakumoto, both acquaintances of the boy.
But the boy told police shortly afterward that it was the 18-year-old who committed the act, police said.
On Feb. 15, the boy filed a complaint against him on suspicion of sexual abuse, and the case was later transferred from the station's community safety section to the criminal investigation section, they said.
The teenager denied the charge and insisted he had an alibi, but police could not confirm it and arrested him March 1.
Because he continued to deny his involvement in the incident, police said they reinvestigated and discovered the boy had also mentioned Kakumoto as one of the suspects.
Kenji Kaneko, head of the Urawa Nishi Police Station, said: "We have caused great trouble to the individuals concerned and would like to extend our sincere apologies. We will do everything we can to prevent a reoccurrence."