An alleged prostitute who solicited business online and a man who accompanied her to Montauk in August pleaded guilty to felony charges on Jan. 11 in connection with the beating and robbery of a would-be client. Keirsten Escobar, 23, of Islip Terrace, who had been in custody since being arrested on Aug. 28, was released and is expected to be sentenced next month to time served, plus five years’ probation. However, Jarryd J. Cox, 31, of Mastic, her companion, will be spending the next couple of years in state prison.In addition, at almost the same time as they were pleading guilty in Criminal Court, the website Ms. Escobar had used, backpage.com, took down adult advertising, for reasons unrelated to this case. The website has been the target of critics for several years, who accused it of facilitating trafficking of minors.The two defendants had faced six felony charges each, several of which were classified as violent, which would have resulted in many years in prison if convicted. For District Attorney Thomas Spota’s office, the prosecution’s witness, Tai Truong, 35, of Springs proved more elusive than the defendants. “On several dates, a grand jury proceeding was scheduled and the local Police Department tasked with finding the victim to serve him with a witness subpoena,” Robert Clifford, spokesman for Mr. Spota, said Monday. “Each time this occurred, it proved more difficult to locate him.” Eventually, Mr. Clifford said, after Mr. Truong was arrested himself on a minor charge by Southampton Town police, “he was served with the subpoena, released on bail, and still failed to appear at our office the following day. Each time the victim left an updated phone number to contact him, the number turned out to be out of service.”In his original statement to police, given at Southampton Hospital after East Hampton Town police had arrested the couple and where he was being treated for wounds inflicted during the robbery, Mr. Truong said he had been staying at a motel on Soundview Drive in Montauk with his girlfriend and her son when he went out alone a little before 10 a.m. to take a drive. He told police that he used his Samsung 7 Edge phone to go to backpage.com’s adult section and clicked on Ms. Escobar’s photograph. She contacted him right away, he said, and they agreed to meet and that he would pay $300 for an hour of sex.He told police that she appeared on Soundview Drive in a green 2002 Ford Explorer, and he thought she was alone. She asked to see the money, and he flashed $700 he had in his wallet. He then had her follow him to a house at 184 Soundview Drive, which had a “for sale” sign. No one was there. They parked their cars facing out, he said, “in case we had to leave quickly.” The two walked to the back of the property toward the beach at Block Island Sound. He reported that he took a blunt, a cigar filled with marijuana, out of his backpack, lit it, and left the backpack at the bottom of the stairs. That is when Mr. Cox appeared, Mr. Truong told police. Mr. Truong said that when he walked over to Mr. Cox he pulled out a long-nosed Heritage .22 caliber revolver and struck him on the side of his head, opening a gash, and knocking him to the ground. Semiconscious and bleeding, Mr. Truong said he felt Mr. Cox go through his pockets and remove his watch and a gold necklace.“I saw him hand my stuff to the girl from backpage.com,” he told police. “He saw me trying to sit up and hit me again with the gun, this time on the nose.” Mr. Truong said he was then bleeding profusely. “I was waiting for him to shoot me.” Instead, Mr. Cox and Ms. Escobar took off. Staggering to his vehicle, Mr. Truong found the doors locked, and went next door where two people called police.Montauk is not ideally situated for those trying to escape the police, with a single two-lane road over several miles as the only way out. An officer spotted the Ford headed west and coming up toward Amagansett. The officer, Andrea Kess, turned on her emergency lights, and Mr. Cox, behind the wheel, pulled over. But after stopping, police said, Mr. Cox floored the gas pedal, headed west, veered across Old Montauk Highway, which is one way in the other direction, and just missed striking a car.With the officer in pursuit, the Ford continued toward Atlantic Avenue, whipping around the intersection and heading north, again almost striking an oncoming vehicle. Mr. Cox continued across Montauk Highway onto Amagansett Fire Department property and smashed through a chain barrier before coming to a stop. Leaving Ms. Escobar in the car, Mr. Cox fled on foot, headed northwest.A manhunt ensued, with East Hampton Village, state, and county officers joining town police, along with a state police K-9 unit and the county’s aviation unit. Police caught up with Mr. Cox at the Balsam Farm stand on Town Lane in Amagansett. He surrendered without a struggle, as did Ms. Escobar.A search of the car turned up Mr. Truong’s backpack, along with his watch and gold chain. Police said a quantity of cocaine was also found in a plastic bag, leading to felony possession charges against the pair.Bail was set for Ms. Escobar at $200,000 by East Hampton Town Justice Steven Tekulsky on Aug. 29. Mr. Cox was not eligible to have bail set in the East Hampton court due to two prior felony convictions. The lawyers each waived their defendant’s right to a timely indictment and trial, to allow time for negotiation.Mr. Cox has a history of criminal violence. He has served time on separate felony convictions of robbery and reckless endangerment in the first degree, a charge that requires the prosecution to prove “depraved indifference to human life.” He also is facing an aggravated harassment charge related to domestic violence and a misdemeanor charge of possession of marijuana, in county jail in November. Mr. Clifford said Ms. Escobar had “denied any pre-existing plan to set up a robbery.”Mr. Truong is also no stranger to the criminal justice system, with a long history of arrests and convictions, including felonies. In 2010, he was indicted on multiple drug charges. He also has been arrested on gun possession charges.Nicholas D. Kristof of The New York Times has documented the activities of backpage.com for some time and interviewed children allegedly bought and sold through the site. The chief executive officer of the site, Carl Ferrer, was arrested last October on a charge, according to The Times, of “pimping a minor,” as well as conspiracy. The website removed its adult content on Jan. 9.The officer involved in the chase, Ms. Kess, is going to be decorated in recognition for her work, Chief Michael D. Sarlo said last week.