If Allen and Petraeus did not approach the FBI, the bureau could not have justified its probe based on a charge of cyberharassment.

FORBES: Was There Illegal Cyberstalking In The Petraeus Affair?

John Yates, the officer in charge of that probe and now the Met's acting deputy commissioner, told two parliamentary committees in March that advice from the CPS had led the force to limit its investigation.

ECONOMIST: The Met has a long way to go to clear its name

"We are confident we have personally contacted all the people who have been hacked or are likely to have been hacked, " Sue Akers, the Metropolitan Police deputy assistant commissioner in charge of the probe, said in a statement.

WSJ: Police Contact Likely Phone-Hacking Victims