HARRISBURG — Democratic Gov. Tom Wolf’s environmental protection secretary resigned Friday after Wolf’s office began looking into an e-mail the official sent to environmental advocacy groups from a private e-mail address.

Wolf confirmed John Quigley’s resignation in a brief interview, but he did not explain the reasons behind it.

The governor said Quigley did a “fine job” and that an acting secretary, Patrick McDonnell, had been named to the Department of Environmental Protection.

The resignation came hours after the governor’s office disclosed its inquiry into the e-mail. Quigley did not return a telephone message Friday.

Sen. John Yudichak, D-Luzerne, said the e-mail inquiry and Wolf’s removal of Quigley was the culmination of growing complaints about Quigley from state lawmakers, both Republican and Democrat, in the GOP-controlled Legislature.

Those complaints had targeted Quigley’s unwillingness to discuss issues, accept feedback and strike compromises, including on a slate of new oil and gas industry regulations, said Yudichak, the ranking Democrat on the Senate Environmental Resources and Energy Committee.

Quigley, he said, had lost the ability to advance the governor’s agenda and had harbored a personal political agenda outside of the Wolf administration.

“There was a pattern of behavior ... that clearly indicated to the governor that John Quigley wasn’t the best person to be the secretary of the DEP,” Yudichak said. “The governor has made that decision; I applaud that decision. He made the right decision and he made it quickly.”

Yudichak said he had not seen the Quigley e-mail in question, sent in April.

In recent weeks, Yudichak became the target of radio and newspaper ads by environmental groups. The ads criticized him for supporting legislation extending the Legislature’s power to seek changes in any Wolf administration plan to comply with federal requirements to curtail greenhouse gas emissions from power plants.

David Masur, president of the environmental advocacy group PennEnvironment, said Quigley had been a strong advocate for the environment and public health in Harrisburg, “where they often don’t have one.”

“It’s unfortunate that this firestorm of innuendo and what feels like a witch hunt played a role in his departure,” Masur said.