media captionFootage of the stop was shared widely on Twitter after being posted by former Olympic 100m champion Linford Christie
Three Metropolitan Police officers will face misconduct hearings over the stop and search of British athlete Bianca Williams and her partner.
Ms Williams and Ricardo dos Santos, whose baby son was in the car, say they were racially profiled when they were stopped in Maida Vale, in July 2020.
The couple were handcuffed and separated from their son.
Three officers are under investigation for gross misconduct, the Independent Office for Police Conduct (IOPC) said.
The three officers were already under investigation for a range of potential breaches of police protocol, including excessive use of force. Three other police officers are also being investigated over the incident.
The Met referred itself to the IOPC after footage of the stop was widely shared, although two reviews by the force's directorate of professional standards have concluded there was no misconduct.
image copyrightJonathan Bradyimage captionBianca Williams believes she was racially profiled
The video was originally posted online by former Olympic champion sprinter, Linford Christie, who trains Ms Williams and Mr dos Santos.
Met Commissioner Dame Cressida Dick has previously apologised for the "distress" caused by the stop.
An IOPC spokesman said: "Three MPS officers are now subject to a gross misconduct investigation for potential breaches of police standards of professional behaviour.
"Our investigatory work has now concluded and preparation of the final report is under way."
Once the report is published, the Met Police will have 28 days to respond before any sanctions are set.
image copyrightEPAimage captionPortugal sprinter Ricardo dos Santos is preparing for the Tokyo Olympics, as is Ms Williams
The Met said it "continues to fully co-operate with the IOPC investigation".
"No officer is suspended or subject to restricted duties," the force said in a statement.
Both athletes are preparing for the Tokyo Olympics.