At his arraignment Friday in Edgartown District Court, William O'Connell, a powerful Quincy developer, pleaded not guilty to charges that he was drunk and operating his 47-foot cigarette boat negligently when the propeller struck and killed his close friend, Quincy real estate broker William Sanderson.

The tragedy happened just before 4 p.m. on the Fourth of July, shortly after Mr. O'Connell landed his speedboat near Chappy Point Beach on the Edgartown outer harbor.

While police had initially charged Mr. O'Connell with fleeing the scene of the fatal incident, prosecutors decided Friday morning to drop that charge.

"I'm not satisfied there's enough evidence on leaving the scene," Cape and Islands first assistant district attorney Michael O'Keefe told the Gazette Friday. "The defendant may well have been trying to get to a place to find out how his friend was doing."

Mr. O'Connell is facing three charges, all misdemeanors. The first two counts of negligent operation of a motor boat resulting in death and operating a motor boat while under the influence of alcohol each carry a maximum jail sentence of two-and-a-half years. The third charge of operating a motor boat within 150 feet of a swimming beach is punishable by a six-month jail term.

In the four days since the tragedy, police and harbor officials have released new details about the incident.

Edgartown harbor master Charles Blair Jr. told the Gazette Friday that Mr. O'Connell had pulled his boat onto the beach on Chappaquiddick to let his son and two grandchildren go ashore.

Mr. Sanderson had helped them off the boat and then walked back into the shallow water along the starboard side of Mr. O'Connell's high-powered boat, Thunder Enlightening.

"He was about midships, working his way to the stern. It's a real high-sided boat. You can't reach the rail. When he got to the corner, he was just gone," said Mr. Blair. "He came shooting out the front underneath the bow."

The harbor master speculated that Mr. Sanderson was trying to reach a swimming platform at the rear of the boat, but the propeller had been left running in reverse gear, sucking the victim into the blades and then underneath the boat.

"I've been around boats all my life and this was the worst propeller strike I've ever seen," Mr. Blair said.

Assistant harbor master Michael Hathaway was on the scene immediately, working with Mr. O'Connell's son and two other men who were on the beach to lift the badly wounded Mr. Sanderson into the harbor master's pump-out boat.

The sharp blades from the 500-horsepower engine had hit Mr. Sanderson in the abdomen. It was a priority one call. Within 10 seconds of landing at the dock of the Edgartown Yacht Club, an ambulance was there to rush the victim to the hospital.

While emergency medical crews were trying in vain to save Mr. Sanderson, state environmental police Sgt. William Searle headed back to the scene to question the pilot of Thunder Enlightening.

"From the time of the incident, it had been just seven to eight minutes. I immediately returned to the scene and [Mr. O'Connell] was already gone," said Sergeant Searle. "He didn't hang around to see how his friend was. He just left."

With blue lights flashing on his 23-foot patrol boat, Sergeant Searle then pursued Mr. O'Connell over the water. "My estimate is that he was going in excess of 70 miles an hour," said Sergeant Searle. "I was seeing nothing but a white plume of water on the horizon by the time he was in Oak Bluffs."

When Mr. O'Connell reached Oak Bluffs harbor, he was placed under arrest by Sergeant Searle and subjected to field sobriety tests. A portable breathalyzer gave police a blood alcohol reading of .06, below the .08 limit at which a person is considered to be legally intoxicated.

But Mr. O'Connell refused to take an official breathalyzer test back at state police barracks. The refusal cost him his motor vehicle driver's license which was suspended Friday for 120 days.

Mr. O'Connell has hired Edgartown attorney Charles Morano to defend him. A pretrial conference is scheduled for July 29.

While Mr. O'Connell simply pleaded not guilty Friday in court, he has spoken publicly, offering his own version of the events. In comments made to the Patriot Ledger newspaper in Quincy, he said that he and Mr. Sanderson had each consumed "a couple beers" after running four miles and then eating breakfast.

Mr. O'Connell said he wanted to bring his boat, which was docked in the Oak Bluffs harbor, back to Chappaquiddick for a beach party the families had planned.

But he was unable to anchor his boat in the harbor, and that's when they pulled up to the beach to let his son and two grandchildren go ashore.

Mr. O'Connell told the Patriot Ledger that he just "lost track" of his friend. Minutes later, Mr. Sanderson was sucked into the propeller blades.

For the next five minutes, Mr.

O'Connell stayed put, but then decided to head to Oak Bluffs where he could take a taxi to the hospital, according to the Quincy newspaper.

"I guess I was in shock," Mr. O'Connell was quoted. "I didn't know what to do. There was no place to dock."

Yesterday, the Gazette received a letter from Mr. O'Connell's family, expressing grief at the death of their close friend and thanking emergency medical crews and hospital staff for their attempts to rescue Mr. Sanderson and console his family and friends.