Greek officials say search teams have found the cockpit voice recorder of the Cypriot airliner that crashed onto a hillside in Athens last Sunday, killing all 121 people on board.

Search teams earlier had found the outer casing of the recorder and the other so-called "black box," which records flight data and will be analyzed by experts in Paris.

The Helios Airways Boeing 737 was flying from Larnaca, Cyprus, to the Czech capital, Prague, with a stopover in Athens.

Investigators believe the aircraft lost cabin pressure, causing sub-freezing temperatures and a sudden loss of oxygen. But the cause of the decompression remains a mystery, as well as why the pilots failed to react.

Earlier Friday, Athens' chief coroner said victim autopsies show the passengers and crew were not overcome by carbon monoxide gas, as investigators had previously thought possible.