The witnesses, who were at the Scotland Yard's headquarters a day after the incident, told the Independent Police Complaints Commission that senior police officers had suspected within hours that they shot the wrong man.
The teenager was hoisted by a Metropolitan Police officer who put him feet-first in the bin. The incident, triggered by an exchange of words between the boy and cops, was captured on a cell phone video by one of Singh's friends.
Earlier, it was reported that the senior officer at the centre of the operation that led to the death of de Menezes had ordered him to be taken alive.