Medfield teen pleads not guilty to charges in Cape Cod boating crash that killed Sherborn girl

BARNSTABLE, Mass. — A Dartmouth College freshman on Tuesday morning pleaded not guilty to charges in connection with a Cape Cod boating crash that killed a 17-year-old Sherborn girl over the summer.

David K. Sullivan, 19, of Medfield, faced a judge more than two months after the fatal boating crash that killed his girlfriend, Sadie Mauro, a Dover-Sherborn High School senior, in Dennis on July 21, according to court documents. Two others were seriously injured.

Sullivan was arraigned Tuesday in Barnstable Superior Court on charges including death of a person caused by operating vessel/boat under the influence of intoxicating liquor, possessing false RMV documents, minor in possession of alcohol, operation of a vessel while under the influence of intoxicating liquor causing serious bodily injury, and reckless or negligent operation of a vessel causing death, according to Cape & Islands District Attorney Robert Galibois.

Sullivan was released after posting $5,000 cash bail and was ordered to surrender his passport.

Sullivan was indicted in late September by a Barnstable County grand jury.

Emergency crews responded to a report of a boat crash in Sesuit Harbor in Dennis on the evening of July 21.

Mauro, a former resident of Shelburne, Vermont who died in the wreck, was a star lacrosse player at Dover-Sherborn High and had committed to playing lacrosse at Gettysburg College next year.

Dover-Sherborn High School Principal John Smith remembered Mauro as “a hardworking student and great athlete.”

A preliminary investigation found that the vessel was equipped with two outboard 250-horsepower engines bearing an Alabama registration, Galibois said.

Charges were filed against Sullivan after an investigation by Dennis Police, Massachusetts State Police, Massachusetts Environmental Police, the State Police Marine Unit, the Massachusetts State Police Dive Team, and the Barnstable County Regional Dive Team.

According to a court memorandum submitted by Sullivan’s attorneys in support of his release, Mauro was Sullivan’s “girlfriend and best friend.”

“Since that date, not a day has gone by that Mr. Sullivan has not grieved with his girlfriend’s family, relieved the horrors of the accident, and prepared for the possibility of having to defend himself against criminal charges,” Boston Attorneys David Meier and Hannah Black, who are representing Sullivan, wrote in their memorandum.

Sullivan is a Dartmouth College freshman who graduated from The Roxbury Latin School in June.

“By all accounts David Sullivan is a bright, hard-working and honorable young man,” his attorneys wrote.

And, Sullivan’s family “have several generations of roots in the Cape Cod Community and the greater Boston community,” his attorneys wrote.

According to his attorneys, immediately after the deadly accident, Sullivan, who was thrown from the boat, tried to help save the people who had been on the boat. He also dove back into the water in search of Mauro, his girlfriend.

“In the seconds, minutes and hours after the accident he acted responsibly and deliberately, with sound judgment and coordinated motor skills and did his best to locate and save the other individuals who had been on the boat, to summon help and to cooperate with police investigators,” his attorneys wrote.

“In the darkness, he managed to swim back to the still running boat, maneuver his way on board, and shut off the engines,” his attorneys wrote.

His attorney said Sullivan spoke several times with investigators after the crash.

“Significantly, at no time during any of these three occasions, did any law enforcement officer request that Mr. Sullivan perform field sobriety tests,” his attorneys wrote.

Sullivan is due back in court on Dec. 14.

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