The man hanged himself to death late Wednesday night at Chinsurah, some 50 kilometres from Kolkata.
Following a complaint, the alleged rapist was arrested Sunday but released after a few hours.
"There was no evidence against the person who was named in the complaint. We are investigating the matter," said an officer of Chinsurah police station.
The officer, however, refused to comment if the alleged victim underwent a medical examination to ascertain rape.