MARCH AIR FORCE BASE, Calif. (AP) _ Investigators examined jet wreckage scattered on a snowy mountainside Friday for clues to the crash that killed actor Dean Paul Martin and his co- pilot.

Funeral and memorial services were pending for the 35-year-old California Air National Guard captain, son of entertainer Dean Martin.

Martin was killed last Saturday at the 5,500-foot level of Mount San Gorgonio along with co-pilot Capt. Ramon Ortiz, 39, of Las Vegas, Nev., authorities said.

Maj. Steve Mensik said Friday authorities have no idea yet what caused the crash of the F-4 Phantom. The results of a six-member team's probe are expected in 30 to 90 days, he said.

Martin and Ortiz crashed while flying at about 400 mph just 10 minutes after takeoff from March Air Force Base. Mensik said the jet's full load of fuel exploded on impact.

The wreckage was found Wednesday, and a preliminary examination has suggested that neither man attempted to use a parachute or eject, Mensik said. The bodies were airlifted from the wreckage site Thursday to March Air Force Base.

The investigators plan to interview people involved with the flight, review the jet's maintenance records and the pilots' records and analyze the Federal Aviation Administration's tapes of the flight, Mensik said.

Investigators also may consider accident reports on other F-4s ''to see if there is a trend that needs to be addressed,'' Mensik added.

A memorial service by the Air National Guard was being arranged for either April 4 or April 5, Mensik said. He said about 1,200 members of the the pilots' 163rd Tactical Fighter Group plan to participate.

Caroline Yablans, an assistant to Dean Martin Sr.'s publicist, Warren Cowan, said funeral arrangements were pending.

''We would think it will be this weekend,'' she said Friday.

Cowan has said the family is ''grief-stricken and in seclusion'' in Beverly Hills.