Documents relating to Maxine Carr's release from prison were stolen from a Home Office official's car while she attended a birthday party in a pub.
The Prison Service says Carr's release will go ahead as planned
The civil servant's Ford Fiesta was broken into outside the Wells Tavern, in Hampstead, north London, on Tuesday.
After she explained what had been stolen to the first police officers at the scene, at least 10 extra officers arrived to search the area.
"At the time I just thought it was another break-in," a pub worker said.
Another member of staff said the incident happened at about 1530 BST.
"A lady ran out of the room saying her car had been broken into. Then police showed up and they looked in the bar," the employee said.
"At that time I didn't really know what they were looking for. They were investigating inside and walking up and down the street looking around."
Extra officers arrived to join the search after the civil servant explained the significance of what had been taken.
The Home Office worker had been personally responsible for drawing up arrangements for Carr's release.
"The lady was frantic," the Wells Tavern worker said. "She had just had her car broken into. We don't get them here that often but it happens.
"Hoodlums know that people around here have money. It was unusual that it happened in broad daylight."
The documents were found abandoned on Hampstead Heath four hours later.
The Home Office has refused to comment on its inquiry into the theft.