The head of the New York State Police, Joseph D’Amico, abruptly announced his retirement on Friday, saying he wanted to “pursue other opportunities.” Mr. D’Amico, who was appointed superintendent on Jan. 31, 2011, did not elaborate on his decision. He agreed to remain in his post while a search for his replacement is conducted.

When Gov. Andrew M. Cuomo tapped him for the job, he hoped that Mr. D’Amico would help repair the image of a police force that had been sullied by scandal and intrigue.

The governor was well acquainted with Mr. D’Amico, who served as Mr. Cuomo’s chief investigator while he was the New York State attorney general. Mr. D’Amico had overseen and coordinated the efforts of 300 criminal and civil investigators statewide, and when Mr. Cuomo selected him to lead the State Police, the governor hoped it would signal a new era.

As attorney general, Mr. Cuomo was well versed in the problems within the State Police and had documented efforts by elected officials to use the agency to go after enemies and protect friends.

His office issued reports criticizing the administrations of the last three governors for misusing the State Police.

“Chief D’Amico brings extraordinary police credentials and a fresh perspective to the State Police, which will be a significant asset in re-establishing the good reputation of this distinguished force,” the governor, a Democrat, said after Mr. D’Amico’s confirmation to the post.

The announcement came in a three-paragraph news release on Friday afternoon, with statements from the governor and Mr. D’Amico.

“He has led the State Police through hurricanes, snowstorms, antiterrorism actions, prison breaks and manhunts,” Mr. Cuomo said. “There is no doubt he has led the State Police to a higher level.”

As the head of the State Police, Mr. D’Amico has generally stayed clear of negative headlines.

In January, he was criticized for intervening in an episode in which a ticket was voided after a vehicle being driven by an off-duty New York Police Department officer struck a marked State Police van.

“Upon reviewing the facts of the case, Superintendent D’Amico directed Troop T to review the decision to issue the ticket,” a State Police spokesman, Beau Duffy, said in a statement at the time. “Troop T determined that the charge was not appropriate for the circumstances of the collision, therefore the ticket was voided.” Mr. D’Amico’s departure was reported by The New York Post.