To become an undercover cop, he had to create a believable 'legend' or criminal cover story.
The Sun
But his luck runs out as it turns out she's an undercover cop.
The Sun
No players took part in the plan, which was exposed by an undercover cop.
The Sun
Once, rapping at the window of a limousine, the driver shooed him away, saying he was an undercover cop.
Times, Sunday Times
The unconvincing undercover cop in the cellar was not believable.
Times, Sunday Times