(Editor’s Note: Strong language in first, fourth and tenth paragraphs)

Milwaukee County Sheriff David Clarke Jr. departs after a meeting with U.S. President elect Donald Trump at Trump Tower New York, U.S., November 28, 2016. REUTERS/Lucas Jackson

WASHINGTON (Reuters) - Milwaukee County Sheriff David Clarke, who said last week he accepted a job with the U.S. Department of Homeland Security, has denied a report that he plagiarized content in his 2013 master’s thesis, calling the story’s reporter a “sleaze bag.”

Clarke, an African-American who became a staunch critic of the Black Lives Matter movement and supported Republican Donald Trump’s presidential campaign, lifted language from multiple sources for his thesis at the Naval Postgraduate School, CNN reported on Saturday.

Clarke provided footnotes for the sources of the thesis, titled “Making U.S. security and privacy rights compatible,” the story by CNN reporter Andrew Kaczynski said. But the thesis failed to use quotation marks where Clarke used passages verbatim, which breaches school guidelines, the network said.

“Guy is a sleaze bag. I’m on to him folks,” Clarke wrote of Kaczynski in a Twitter post late on Saturday. The post linked to a story in which Republican Senator Rand Paul of Kentucky pushed back against a Kaczynski story for Buzzfeed News, in which he was accused of using disputed quotes.

The Milwaukee Journal Sentinel reported that Clarke said in an email to the paper, “Only someone with a political agenda would say this is plagiarism.”

The Naval Postgraduate School, in Monterey, California, did not respond to a request for comment.

On Twitter, Kaczynski wrote on Sunday, “Sheriff Clarke has yet to respond to the substance of our story.”

Clark said on Wednesday that he had accepted a job as assistant secretary at the Department of Homeland Security. In a radio interview, he said he would act as a liaison with state and local police and governments and with the private sector.

David Lapan, a department spokesman, said by email that no announcement on Clarke had been made.

Clarke spoke in support of Trump at the Republican National Convention in Cleveland last July. He has criticized the Black Lives Matter movement, which grew out of protests over a number of police killings of unarmed black men, as “subhuman creeps.”

Critics have faulted Clarke for his management of a Milwaukee County jail where a mentally ill man died in 2016 of dehydration after seven days without water. An inquest jury recommended that seven employees of the jail be criminally charged.