Ryan Lochte and his fellow American swimmers "were not victims of the criminal actions they claim they were", according to police in Rio de Janeiro.
Lochte - along with James Feigen, Gunnar Bentz and Jack Conger - claimed to have been robbed at gunpoint after leaving a party on Sunday.
However, scepticism about the athletes' version of events mounted, with reports on Thursday suggesting Lochte became involved in a physical confrontation with a petrol station security guard on the night in question.
CCTV footage was also leaked which claimed to show the swimmers returning to the athletes' village following the alleged incident with their possessions, casting further doubt on assertions their wallets were stolen.
And, while police confirmed use of a weapon to "control, probably, one of them" after causing damage at the petrol station, they insist surveillance footage showed "no violence" towards the swimmers.
In quotes translated by CNN, Rio's chief of civil police Fernando Veloso said: "When they left that party, they stopped at a gas station, they went to the bathrooms as the surveillance video has shown.
"They deliberately - one, or all of them - started to vandalise the bathroom inside of the gas station, damaging some mirrors and things that they had inside that bathroom.
"With this altercation, some employees from the gas station tried to control that situation as the surveillance video showed.
"The images also showed the athletes going back to the taxi and trying to get away from the gas station.
"When the gas station employees realised what was going on there, the security guards asked the taxi driver to not leave that place and wait for the police to arrive. We have also asked for a police report that they were asked to go to this place.
"The athletes, they refused to stay there, they didn't want to wait for the police to arrive. During that time a third person offered to be a kind of interpreter because the security guard of the gas station didn't speak English and the athletes didn't speak Portuguese, so this third person is going to be heard.
"What the police can affirm is that there was no robbery the way it was reported or claimed by the athletes. They were not victims of the criminal actions that they claim they were. The police can affirm that."
Bentz and Conger were prevented from leaving Brazil and had their passports seized by police on Wednesday as the investigation continued. Lochte is thought to have returned to the US, while Feigen's whereabouts are unclear.
The swimmers could yet be charged with criminal damage and the false reporting of a crime, although Veloso stressed the need to complete the investigation before discussing consequences.