In a deal sealed in June, Oak Bluffs selectmen handed their police chief, Joseph C. Carter, a one-time check for $67,882 in overtime pay, almost equal to his current annual salary of $70,000.

And while both the chief and the town's top selectman say the 2,155 hours of overtime filed by Chief Carter are entirely legitimate and were logged over the last three years, the town finance committee is raising questions and has already begun an investigation.

"It seems there was an awful lot of comp time paid, and I don't know why yet," said finance committee chairman Russell Rogers. "We're still doing our own research."

According to documents obtained by the Gazette and based on comments made by Chief Carter this week, the town also paid their top law officer for another 1,000 hours of overtime in his first two years as chief, an amount totaling roughly $30,000.

All told, Chief Carter has collected just under $100,000 in overtime pay for this first three years on the job. The extra hours worked mean Chief Carter has billed Oak Bluffs for an average 20 additional hours during each week of his tenure. His salary in his first three years was $65,000 a year.

Neither of the two other down-Island towns pay their police chiefs overtime. In Edgartown, if the police chief works more than 40 hours a week, he is entitled to accrue hours and take time off later. In Tisbury, officials said, the chief earns a base salary no matter what the hours.

In Oak Bluffs, Chief Carter's contract spells out that while he is expected to spend whatever time is necessary to do the job, the work week consists of 40 hours. Anything beyond that entitles the chief to "compensatory time off."

But while the contract does not specifically mention paying the chief money for overtime, chairman Michael Dutton of the board of selectmen said this week that it's common practice to buy back so-called comp time.

"We paid for the comp time instead of letting him take the time off," said Mr. Dutton. "Selectmen have that option, and we felt it was in the best interest of the town."

Mr. Dutton fully backed his board's decision to pay the chief the sum of money, saying that when Chief Carter was hired in May 1998, he inherited a department that was understaffed.

"In all fairness, you have to look back and realize that we were short-staffed and without a sergeant and a lieutenant for a number of years," he said.

Mr. Carter came to Oak Bluffs with 20 years of experience in the Boston police department, where he was promoted to high levels, working closely with the city's police commissioner.

Mr. Dutton said that his board never questioned the veracity of the police chief's overtime hours. Detailed records, he said, were filed with the town accountant. Accountant Tom Wilson told the Gazette he needed a few days to locate and provide those records.

Chief Carter yesterday defended his overtime pay, saying that it was not only "hardearned and wellearned" but also covered by his contract.

"On a regular basis, I'm there before the sun comes up and stay until late at night, working on grant proposals and at meetings to support bringing this department into the 21st century," he said.

Of his first years on the job, the chief added, "People in the town can attest to the fact that I was literally omnipresent. I worked 20-hour days during the Fourth of July. I worked weekends and holidays while everybody else was away."

Chief Carter also used to attend regular selectmen's meetings, but he stopped abruptly last year. Mr. Dutton said his board no longer needed the chief's help to keep order. Privately, one selectman said the chief had been billing the town overtime hours for this service, and the board decided it didn't want to keep paying him.

Besides putting in overtime as police chief, Mr. Carter is also a colonel in the Massachusetts Army National Guard and is currently serving as base commander at the Massachusetts Military Reservation, Camp Edwards, in Otis.

Chief Carter, who spoke to the Gazette yesterday from his office at Camp Edwards, said his Army work takes him off-Island or away from the police station four days a month, two of those days being weekends.

As commander of the 40,000-acre training site, Mr. Carter is responsible for all property, personnel and any training activities. A member of the Guard for 26 years, he earns an additional $18,000 a year for his service.

This past year, Chief Carter also campaigned to become vice president of the International Association of Chiefs of Police, creating a five-page web site and traveling off-Island for a total of one week to support his election bid. Yesterday, the chief said that the other candidates for the post have pulled out of the race, assuring him of a victory.

Finally, in addition to his police work, Army responsibilities and political campaigning, Mr. Carter is also attending graduate school at the U.S. Army War College. While the school is based in Carlisle, Pa., the chief said the master's degree in strategic studies is a distance education course that requires only two weeks of actual on-site military training.

"I work seven days a week, a combination of military, police and studying," he said. "I go almost the whole month. I get an hour or so for dinner with my family. Otherwise, I'm working."

Mr. Dutton said, "People look at that and say, the chief's not there as much as he should be, but I look at that as the opposite. In banking, we call it soft dollars. The knowledge base and experience he brings back to the town are invaluable, and his involvement in his profession is beyond our expectations."

Chief Carter said that his Army connections have benefited the entire Island. He pointed to the construction of a ropes course near the airport by National Guard troops and the fact that Island police can now use the firing range at Camp Edwards rather than resorting to a sand pit on the Vineyard.

Mr. Dutton said he does not expect to see Chief Carter logging the same kind of overtime now that the police department is fully staffed. Indeed, in the chief's short tenure, he has doubled the budget by hiring new police officers and top brass.

"It would be our intent not to do this again," Mr. Dutton said of the chief's overtime pay. "It's not his intent to ask again, and I suspect we would not permit the same type of comp time to accrue."