Former Costa Rican President Óscar Arias has been accused of sexually assaulting a woman in 2014.
Mr Arias, who is 78 and has won the Nobel Peace Prize, categorically denied the allegations and said he had always treated women with respect.
His accuser, a peace activist, has filed a formal complaint with police.
She told local media and the New York Times that he had groped her after they met at his home to discuss his support for a campaign against nuclear weapons.
Mr Arias was president twice, from 1986 to 1990 and then from 2006 to 2010.
- Costa Rica country profile
He won the Nobel Prize in 1987 for his efforts to end civil wars in several Central American nations.