ATHENS, Greece — Carbon monoxide did not knock out some of the passengers and crew of a Cypriot airliner before it crashed in the Greek mountains, coroners said yesterday, deepening the mystery as to what caused the disaster that killed all 121 people on board.

Fillipos Koutsaftis, chief coroner of Athens, said tests were carried out on the remains of the co-pilot, three female flight attendants, an infant and an adult who were on the flight that crashed Sunday 25 miles north of the Greek capital.

More tests were being conducted to determine what could have rendered crew and passengers aboard the Helios Airways Flight ZU522 from Larnaca, Cyprus, unconscious during the flight. The plane flew on autopilot before crashing.

Koutsaftis said a few more days were needed to run the toxicological tests.

"This was the fastest test and the most secure," he said after meeting Justice Minister Anastasios Papaligouras. "We are still doing tests for other gases, poisons, drugs and alcohol."

Earlier tests showed that at least 26 people on the flight were still alive when it crashed. There has been speculation that an electrical fire or some other cause could have flooded the cabin with carbon monoxide or another gas.

Investigators also have been examining whether a sudden decompression sucked oxygen out of the cabin and cockpit and rendered those on board unconscious.

Grief in Venezuela

MARACAIBO, Venezuela — Scores of grieving relatives arrived in Venezuela from the French Caribbean island of Martinique yesterday, while DNA samples and dental records were used to try to identify the remains of the 160 people killed in a plane crash this week.

West Caribbean Airways' safety record is under scrutiny by Colombian civil aviation authorities and its flights have been grounded while officials review inspections that the carrier had been required to perform.

The airline has said that it didn't cut corners on safety and that the plane passed a safety inspection in Colombia the day before it crashed.