"I made mistakes," Olesker said as he cleaned out his desk.
Olesker wrote a twice-a-week column in the Maryland section for 27 years, having served in other capacities for two years. His most recent column appeared Tuesday, his last day.
"I am sorry to say that in the course of doing those columns, I unintentionally screwed up a handful of paragraphs. I am embarrassed by my sloppiness," he said.
Neither Olesker, 60, nor Editor Timothy Franklin returned calls Wednesday made by The Associated Press.
The allegations surfaced Tuesday in an e-mail from Gadi Dechter, a media reporter at the Baltimore City Paper, an alternative weekly, to Sun City Editor Howard Libit.
Dechter said he and a researcher had reviewed Olesker's columns during the past two years and found instances in which the columnist had apparently used the work of journalists at The New York Times, The Washington Post and The Sun without attribution.
Dechter's research was prompted by a Dec. 24 correction in The Sun in which the paper said a paragraph from a Dec. 12 column by Olesker about former Sen. Max Cleland was almost identical to lines in a 2003 profile by Peter Carlson of The Washington Post.
Carlson wrote: "On one of his first trips out of the hospital, an old girlfriend pushed him around Washington in his wheelchair. Outside the White House, the chair hit a curb and Cleland pitched forward and fell out. He remembers flopping around helplessly in the dirt and cigarette butts in the gutter."
Last month, Olesker wrote: "On one of his first trips out, an old girlfriend pushed his wheelchair around Washington. Near the White House, the wheelchair hit a curb. Cleland pitched forward and fell out, flopping around in dirt and cigarette butts in a gutter."
A review of Olesker's work by The Sun was under way when he resigned.
"Clearly, this is a practice that's unacceptable, and we acted quickly to meet with Mike and try to resolve it," Franklin said in The Sun. "It's been excruciatingly painful."
Olesker and Sun political editor David Nitkin are central figures in a First Amendment lawsuit the newspaper has filed against Gov. Robert Ehrlich.
In November 2004, Ehrlich issued an order prohibiting executive branch employees from speaking with Olesker and Nitkin. The ban was imposed after Nitkin disclosed a state proposal to sell preserved forestland in St. Mary's County to a politically connected construction company.
Press secretary Greg Massoni said in the e-mail detailing the ban that Nitkin and Olesker "are failing to objectively report on any issue dealing with the Ehrlich-Steele administration."
The governor's staff had complained about a November 2004 column in which Olesker described a meeting that he did not attend. Olesker acknowledged that he did not attend the meeting and apologized.
The governor's office also accused Olesker of concocting a conversation with Lt. Gov. Michael Steele in May 2004. But a few days after leveling the accusation, Ehrlich's office retracted it and acknowledged that Steele had spoken to the columnist.