LEWISTON — Dr. David York, a family practitioner with an office in downtown Lewiston, was arrested and charged Tuesday with five counts of possession of sexually explicit materials of children under the age of 12.

York, who lists his address with the Maine Board of Licensure as Charlotte, N.C., was licensed to practice medicine in Maine in 2008. He was arrested at his home at 212 Congress Circle in Topsham.

York, 59, is a medical doctor employed by Concentra Medical Centers, a national health care company that has offices in Augusta and Lewiston. According to police, York treated patients in both locations.

Maine’s chief of State Police, Col. Patrick Fleming, said two computers were seized from York’s home by the Computer Crimes Unit. Preliminary examinations show “hundreds of images and videos of child pornography,” Fleming said.

He said there was no indication that any of the images were of Maine children.

Most of the images, Fleming said, were from file sharing with other personal computers around the country, also known as a “peer-to-peer network.”

York’s activities came to the attention of state police in November.

Michael J. McFadden, who works at the Maine State Police Computer Crimes Unit, said in a sworn affidavit that York logged onto the Internet and shared child pornography at various times, including Dec. 4. York was identified through his Internet Protocol address — a numeric address given to a computer connected to the Internet — with service provider Comcast, which answered a subpoena.

In February, McFadden found 312 instances of child pornography videos being shared using York’s Internet identity.

A month later, McFadden checked the same Wyoming database to see whether York’s Internet identity had any new activity. Four days earlier, 16 files had been viewed in the shared file directory associated with his identity, McFadden wrote in court papers.

On Tuesday, McFadden went to Maine District Court Judge John D. Kennedy with an affidavit and a warrant to search York’s home in Topsham.

McFadden wrote that on Tuesday morning, York admitted downloading “a large number” of videos and still images depicting children engaged in sexual acts. York said he wasn’t a pedophile, “per se; however he does have an interest in viewing pornographic material depicting children engaged in sexually explicit acts,” McFadden wrote in his affidavit.

Police seized two computers from York’s home. Analysis showed a “large amount” of child pornography was found in a user-created file. York phoned McFadden who had already left the home to say that he would find images of child pornography on several compact disks taken from York’s home.

A spokesman for Concentra Inc. said Wednesday that York’s employment had been terminated.

John Delorimier called York’s arrest and charges a “tragic situation.”

York had worked for a year as an occupational medicine doctor, meaning he responded to workers’ compensation claims at the Lewiston clinic, one of Concentra’s 314 medical centers in 40 states. Although Concentra’s Maine clinics provide urgent care, they’re not advertised as such, Delorimier said.

For that reason, York wasn’t likely to have treated children. “We doubt that he has,” Delorimier said.

York was taken to Two Bridges County Jail in Wiscasset, where he was booked and released on $2,500 cash bail, a jail worker said Wednesday.

According to a complaint filed at Sagadahoc County Superior Court in Bath, York was charged with five counts of possession of sexually explicit materials, all Class C crimes. Each count is punishable by up to five years in prison.

York’s Maine license to practice medicine is scheduled to expire at the end of 2010. He attended medical school at the University of Toronto Faculty of Medicine in Canada, graduating in 1981. His specialty is listed as “family practice.”