HENDERSON, Nev. - A federal crash investigator said Friday that a Las Vegas tour helicopter that crashed, killing all five people aboard, made a sudden climb and sharp turns moments before plunging into a canyon near Lake Mead.

National Transportation Safety Board member Mark Rosekind said he could not draw conclusions about the cause of the Wednesday crash from the erratic flight pattern and said the investigation would continue.

"Up to the last minute, it was all standard tour operating procedure," Rosekind said. "At the last minute, things changed. Why? We don't know."

Rosekind said the fatal flight was the fourth for the aircraft after it underwent routine mainten-ance Tuesday to replace the engine and mechanical actuators.

An initial engine examination found the engine was producing power at the time of impact, and Rosekind said all the mechanical control devices, called servo-actuators, were removed from the wreckage Friday to be examined.

Authorities removed bodies from the crash site Thursday but didn't immediately release the names of the five people who perished in the fiery crash of the AS350BS helicopter operated by Sundance Helicopters of Las Vegas.

Clark County Coroner Michael Murphy said he couldn't release the names of the victims because they have not been fully identified, a process that will likely involve the use of DNA, fingerprint and dental records.

Family members have identified three of the dead as the pilot, Landon Nield, 31, of Las Vegas, and Delwin and Tamara Chapman, both 49, of Utica, Kan., who were celebrating their 25th anniversary. Murphy said Friday the other two victims were a couple from New Delhi, India.

Weather did not appear to be a factor in the crash. Skies were clear with breezes of about 5 mph.