RIO DE JANEIRO — Police investigating reports that American swimmer Ryan Lochte and three of his teammates were robbed at gunpoint in a taxi so far have found little evidence supporting the account, and say the swimmers were unable to provide key details in police interviews.

A police official with knowledge of the investigation told The Associated Press that police cannot find their taxi driver or witnesses. The official spoke on condition of anonymity because the investigation is ongoing.

Lochte’s attorney, Jeff Ostrow, said there was no question the robbery happened and that Lochte had 24-hour security hired after the incident. He had been staying in his hotel room and intended to go back to the U.S. soon.

“This happened the way he described it,” Ostrow said.

According to statements from Lochte and the United States Olympic Committee, the swimmers were returning to the athletes village by taxi after a night out at the French Olympic team’s hospitality house in the Rodrigo de Freitas area in the upscale south zone of the city. The outing was several hours after Olympic swimming ended Saturday night at the Rio Games.