Basing his opinion on eyewitness accounts, Bennett said the aircraft probably malfunctioned and lost power to its engines. When this emergency--known as auto-rotation--occurs, the pilot must reverse the angle of the aircraft's propellers and keep the helicopter airborne by forcing air through the engine.

At the time of the crash, the aircraft was heading west towards Cambridge when it suddenly banked to right and fell at a45 degree angle. The rotor was not turning at thetime of impact, observers said.

"I saw it for a blink of an eye, for less thanten seconds," said Barber. "As I turned around, Isaw the tail section hit the roof."

The cause of the crash is being investigated bya host of state and federal agencies, includingthe state police, the National TransportationSafety Board, the Federal Aviation Administration(FAA) and the Massachusetts AeronauticsCommission.

Bennett said the "A" Star 350 "B" AmericanEurocopter was not equipped with a black boxemergency recording device.

The chopper was one of two owned by the statepolice. This model of helicopter has been involvedin 24 accidents since 1983, six of which werefatal, news broadcasts reported yesterday.

The chopper's debris was scattered for at least200 yards around the scene, reaching as far as theisland in the center of Memorial Drive, accordingto Harvard Police Lt. Lawrence J. Murphy, whoarrived on the scene roughly ten minutes after thecrash.

Rescue workers were drawn to the scene by thebuilding's fire alarm which was set off by theimpact, according to Joe Wrinn, acting director ofthe Harvard News Office. "It was that alarm andeyewitness action that got everybody moving," hesaid.

The scattered parts were roped off by policewho waited for an FAA official to inspect thescene.

At approximately 3 p.m., the debris was loadedin two pieces onto a large, flat-bed truck andtaken to a site near Logan Airport where theremains of the helicopter will be examined, Murphysaid.

"We will reconstruct the aircraft piece bypiece," Bennett said. "They should be able to comeup with a good idea of why it crashed."

At a press conference yesterday afternoon, Gov.William F. Weld '66 said he was grieved by thehelicopter crash, which is the first in StatePolice air-team's 26-year history. "This is thefirst accident involving a state policehelicopter," Weld said, speaking at an impromptupress gathering at the Lower Basin policeheadquarters, "We will all work hard to make sureit is the last."

Bennett described the two trooperpilots asdevoted "family men."

Mattaliano is survived by his wife Jennifer, afellow State Police officer whom he met andmarried in August of 1993 while serving onMartha's Vineyard.

The couple recently purchased a home inSandwich, Bennett said.

Perry, who is also anattorney, is survived byhis wife Carol and their two children.