“I believe that my resignation will help to ensure that there is no false conflation with events at a separate organization,” Mr. Murdoch, 39, wrote in a letter to the BSkyB board, referring to News International, the British newspaper arm of his father’s media empire. He resigned as chief executive of News International five weeks ago.

Mr. Ryley of Sky said Thursday that one of the e-mail hacking cases occurred in 2008 and concerned John Darwin, a Briton who staged his death in a fake canoeing accident in 2002 but actually moved to Panama and, in collusion with his wife, collected £500,000 in life insurance.

Known in the tabloids as the “canoe man,” Mr. Darwin returned to Britain and lived in a secret apartment in his old house until 2007, when he turned himself in to a police station, claiming at first to have no idea what he had been doing for the last five years.

The next year, a Sky News reporter pursuing the story sought permission to hack into e-mails he suspected had been used by the Darwins to communicate after Mr. Darwin’s fake death, Mr. Ryley said in an online posting.

“After careful consideration, Sky News granted permission because we believed the story was justified in the public interest,” Mr. Ryley said. “None of the material obtained was broadcast prior to the conviction and our coverage made clear that we had discovered and supplied e-mails to the police. There has been no attempt by Sky News to conceal these facts, which have been available on our Web site ever since.”

In a statement, the police department in Cleveland, which handled the Darwin case, said that it had “conducted an initial review into these matters and can confirm that inquiries are ongoing into how these e-mails were obtained.”

A second case involved e-mails relating to a suspected pedophile, a spokeswoman for Sky News said. On both occasions, she said, the managing editor of Sky News, Simon Cole, authorized the hacking.