Police sources and videos emerging on Thursday seemed to contradict the armed robbery account that the Olympians provided earlier this week.
The four swimmers, Ryan Lochte, James Feigen, Jack Conger and Gunnar Bentz, previously said men posing as police officers pulled their taxi over near a gas station and took their valuables early on Sunday.
"The guy pulled out his gun, he cocked it, put it to my forehead and he said, 'Get down,'" gold medalist Lochte said. "He took our money, he took my wallet - he left my cell phone, he left my credentials."
However, the police were quick to note discrepancies and contradictions in the story told by the four athletes. Also, the authorities apparently noted that the swimmers still wore their watches while returning to the Olympic village, according to the security footage.
This prompted a judge to order the American athletes to stay in Brazil and seize their passports.
Judge Keyla Blank also commented that the swimmers gave apparently conflicting statements, including the number of alleged robbers.
"It's noticeable that the victims arrived back physically and mentally unshaken, even joking with each other," the judge added.
Although Lochte already returned to the United States, Brazilian police pulled his teammates Conger and Bentz from a US-bound plane late Wednesday. Feigen is also believed to still be in Brazil.
On Thursday, a police official close to the investigation told the AP news agency that Lochte fabricated the robbery story.
The source said the swimmers stopped at the gas station and tried to open a locked bathroom door, and eventually broke it. After that, they tried to leave, but were confronted by the station's security guard. The guard was armed, but never drew his weapon, the official said. Police said, however, that security guards did point guns at the US athletes.
'Let's give these kids a break'
While taking to reporters on Thursday, the gas station staff said they believed the athletes had only torn down a poster from the wall, rather than breaking the door.
On the same day, Brazilian Globo TV aired a video from the station's security cameras showing the athletes arguing with the security guard. The guard ordered them to sit on the ground with their hands up.
Bentz and Conger were seen entering a Rio police station on Thursday.
The authorities suspect them of giving "false testimony," local Olympic Organizing Committee spokesman Mario Andrada said. They could also face probation, suspension, a fine, or expulsion under USA Swimming's code of conduct.
Although the robbery story caused a lot of negative publicity during the Rio games, Andrada defended the athletes, saying they were "kids" competing under "gigantic pressure."
"Let's give these kids a break. Sometime you take actions that you later regret," Andrada said. "They had fun, they made a mistake, life goes on."
The United States Olympic Committee (USOC) apologized on Thursday to the people of Brazil for the behavior of the swimmers. The body acknowledged that one of its athletes had committed an act of vandalism in a gas station restroom and the swimmers had handed over money to security staff after they'd demanded payment for the damage in the early hours of Sunday.
"The behavior of these athletes is not acceptable, nor does it represent the values of Team USA," USOC chief executive Scott Blackmun said in a statement released on Thursday night.
dj/sms (dpa, Reuters, AP, AFP)