‘The credible lead is somebody whose possible connection to the hijacker is strong,’ she told the Daily Telegraph. ‘And the suspect is not a name that’s come up before.’

The FBI said that an item belonging to the suspect has been sent for testing at a forensics lab in Quantico, Virginia.

‘We’re hoping there are fingerprints they can take off of it,’ she said. ‘It would be a significant lead.

And this is looking like our most promising one to date.’