PEABODY - A Beverly patrolman pleaded not guilty at his arraignment yesterday on vehicular homicide charges, as his lawyer now appears to be backing away from claims that the crash was caused by a sudden acceleration of the police cruiser.

A clerk magistrate found probable cause earlier this month to believe Stuart Merry, 40, was negligent on the morning of Jan. 20, when his cruiser crashed into a parked car and killed the woman inside.

Bonney Burns, 61, had parked outside her home on the corner of Cabot Street and Columbus Avenue to unload groceries when Merry's cruiser - traveling 55 miles an hour - veered across the road and crashed into her Toyota, crushing her.

For months, defense lawyer Neil Rossman has cited a string of complaints from other officers and Merry about a sudden acceleration problem in three 2005 and 2006 Ford Crown Victoria police cruisers and has suggested that's what happened on the morning of the crash.

A state police trooper who investigated the crash testified at the clerk's hearing that in the 111/2 seconds before the crash, the cruiser accelerated from 8 mph to 55, with no effort to brake, steer or otherwise try to slow the car and avoid the collision.

And that, Rossman said yesterday after the hearing in Peabody District Court, points more to a medical problem. He said the failure by Merry to take any measures to avoid the crash, as well as testimony from an eyewitness who could not see Merry behind the wheel just before impact, is "substantial evidence that he had some kind of medical emergency."

While Rossman cannot say for certain that Merry suffered a seizure, he said the officer suffered a subsequent seizure in March.

Merry has been on paid administrative leave since the crash.

In the year before the crash, Merry had missed 111 days of work and had returned from another 21-day absence just one day before the crash. Police have refused to comment on the specific reasons for Merry's absence.

During Merry's arraignment, Peabody District Court Judge Allen Swan ordered Merry not to drive while the charges are pending.

In addition to vehicular homicide while driving negligently, a misdemeanor, Merry is charged with driving without a license, failing to stay within marked lanes and speeding. If convicted of the vehicular homicide charge, he could face up to 21/2 years in jail and would lose his license for 10 years.

A pretrial hearing was scheduled for next Tuesday, where Rossman said he expects to receive copies of the evidence prosecutors will use in the case.

He said yesterday that he would like to try the case as quickly as possible, even before Christmas, though it was unclear whether the court's schedule would accommodate such a request.