One of the pivotal members of the Montauk drug ring broken up by police last summer is headed to state prison for six years. Justice Timothy Mazzei sentenced William Crespo-Duran, 35, in Suffolk County Criminal Court yesterday.Known as "Flaco" (Skinny), Mr. Crespo-Duran was one of 17 defendants arrested in August, following a five-month investigation by the Suffolk County District Attorney's East End Drug Task Force into the sale of cocaine and pills in Montauk. What the D.A.'s office police called the largest narcotics distribution ring in and around Montauk at the time—- the height of the summer season — raked in as much as $100,000 in three weeks.Most of the defendants are from Puerto Rico and worked at seasonal jobs in Montauk, mainly in restaurants, returning to Puerto Rico in the winter. Police used court-authorized eavesdropping and electronic surveillance as well as undercover drug buys in the course of the investigation. Then, on Aug. 15, they executed a search warrant at Mr. Crespo-Duran’s house on Gates Avenue. They found 200 grams of cocaine in a compartment in the floor under his bed, according to William Nash, an assistant district attorney with the county narcotics bureau, who called him "a pivotal member" of the drug organization. Police also reportedly found a scale and $18,000 in cash.Mr. Crespo-Duran, who had no prior record, was one of seven named in a 33-count indictment handed down by a grand jury on Aug. 24. He had been facing eight and one third to 25 years on the conspiracy charge alone. He pleaded guilty on Feb. 20 to second-degree criminal possession of a controlled substance for possessing over four ounces of a narcotic, a top A felony. Two other felonies, criminal possession of a narcotic with intent to sell and first-degree conspiracy, along with a misdemeanor charge of criminal use of drug paraphernalia, were covered by the plea. He has been in the county jail, where he was held on $1.5 million bond or $750,000 cash bail, since August, and will get credit for time served. When he gets out of prison, he will be under post-release supervision for five years, according to the D.A.'s office.Robert Coyle, Mr. Crespo-Duran's attorney, said his client expressed remorse for his actions and apologized to the community for his choices and expressed his love for his family. Several of his co-defendants have also taken plea deals. Last month, Antonio Ramirez-Gonzalez, a 30-year-old described by the D.A.'s office as the "gatekeeper of the ill-gotten proceeds," was sentenced in the same courtroom to a prison term of three to nine years.The cases against the alleged leaders of the drug ring, Geraldo Vargas-Munoz, 37, and Elvin Silva-Ruiz, 40, are still pending. Mr. Vargas-Munoz is facing 25 years to life.