When he pulled into the parking lot of the Meadow Glen Mall in Medford, State Police Sergeant Brian O'Hare believed he was about to meet the 14-year-old boy he had been courting for months on the Internet, and the two would have sex, authorities said yesterday.
But there was no boy, just FBI agents waiting to arrest O'Hare at the end of a six-month undercover sting in which agents posed as flirty teenagers on an AOL chat room dubbed BoysShowerM4, said FBI spokeswoman Gail A. Marcinkiewicz.
Well known among his 2,300 peers in the State Police, O'Hare is a 19-year veteran of one of the state's most respected law enforcement agencies. After his arrest Friday, he was charged in federal district court in Boston with coercion and enticement of a minor under 18 to engage in prostitution or sexual activity.
If convicted, O'Hare could face five years in prison.
O'Hare's case seemed sure to rattle the State Police, an agency that prides itself on a special dedication to integrity, professionalism, and protecting the vulnerable.
Yesterday, Lieutenant Sharon S. Costine, a State Police spokeswoman, who said she knew O'Hare, released a brief statement on the arrest.
''The Department is aware of the arrest and the seriousness of the allegations made against Sgt. Brian O'Hare," Costine said in the statement, which she e-mailed to the Globe. ''The Department will be monitoring the proceedings as they progress."
Costine said the State Police also held a hearing after O'Hare's arrest and decided to suspend him without pay. O'Hare, a Lancaster resident, had worked in the State Police's Troop C headquarters in Holden. He could not be reached for comment yesterday and Costine declined to comment beyond her statement.
Starting in August, O'Hare, using the screen name Ranger1777, began chatting on AOL with an FBI agent who described himself online as a high school freshman, Marcinkiewicz said.
Over the next several months, the sergeant and the agent chatted a ''number of times," and ''the nature of the conversation was very sexually explicit," Marcinkiewicz said.
At one point, the agent sent a photo of a teenage boy to O'Hare, and told the sergeant it was a photo of himself, Marcinkiewicz said. In return, O'Hare sent the agent a photo of a man dressed in his underwear, with his face not visible in the shot, saying it was a photo of himself, she said.
At no point did either man reveal that he was a member of a law enforcement agency, Marcinkiewicz said. The men had never met until Friday, when they arranged to rendezvous at the Meadow Glen Mall in Medford.
After his arrest, O'Hare made a brief appearance before a magistrate at the John Joseph Moakley Courthouse in Boston and was released on $50,000 unsecured bail. Marcinkiewicz said O'Hare is expected to return to the court tomorrow to sign over property or some other form of collateral for the bail.
Contacted yesterday, John P. Coflesky, president of the State Police Association of Massachusetts, the troopers' union based in Worcester, said he learned of the arrest from the Globe. He said he knew O'Hare and declined to comment further.
Marcinkiewicz said FBI agents regularly patrol online for suspected sexual predators.
The FBI has made online crime the bureau's third-highest priority, behind efforts to combat terrorism and to gather foreign counterintelligence, Marcinkiewicz said.
Past cases have led to the arrest of people from many professions dedicated to protecting others, among them law and medicine, she said.
''We find these cases are far-reaching," Marcinkiewicz said. ''We have all different kinds of people."