JACKSON, Miss. (AP) — Critics say the Mississippi auditor is wasting time and threatening academic freedom by investigating a tenured professor who participated in two-day "scholar strike” designed to bring attention to police brutality and other issues of social injustice.

Auditor Shad White, a Republican, sent a letter Monday to University of Mississippi Chancellor Glenn Boyce about sociology professor James Thomas, the Clarion Ledger reported.

White's letter said Thomas participated in Sept. 8-9 work stoppage. The nationwide effort involved professors and others halting their classes and other duties.

The letter said state law bans strikes or any other “concerted work stoppage.” White told Boyce that the university should recover money it paid Thomas for those days of work and should go to court to try to remove him from his job. Thomas was granted tenure in 2019, which gives him additional job security.

Jarvis Dortch, an attorney who is executive director of the American Civil Liberties Union of Mississippi, told The Associated Press on Wednesday that he does not think Thomas’ participation in the “scholar strike” constitutes a strike under state law because Thomas was not demanding improvements in his own work conditions but was trying to draw attention to other issues.

Dortch, who served as a Democratic state representative before going to work for the ACLU in July, also said White’s investigation could threaten academic freedom.

“Why is he expending taxpayer dollars on something like this?” Dortch asked.

In an interview with the Clarion Ledger, White said his office has been gathering documents and sent two agents to Thomas’ home last week. He said Thomas wasn’t interested in talking.

Thomas declined to comment to the newspaper Tuesday, and he did not immediately respond to a message from the AP on Wednesday. Thomas retweeted several comments from people who defended him and said the auditor should be going after those who owe the state millions of dollars in misspent money instead of targeting a professor for protesting racism.

An university spokesperson said Ole Miss does not comment on personnel matters. In White's letter, the auditor thanked Boyce and the university for being “very cooperative in this matter.”

White said he began pursuing the case after seeing Twitter posts from Thomas about the scholar strike. White said he also found an email Thomas sent to his students about the strike that “was circulating on the internet.”

White was appointed state auditor in July 2018 by then-Gov. Phil Bryant, a Republican. After Brett Kavanaugh was confirmed to the U.S. Supreme Court in October 2018, Thomas came under broad criticism by conservatives after the professor said on Twitter that people should disrupt U.S. senators' meals. “They don’t deserve your civility,” Thomas wrote.

Bryant, at the time, criticized Thomas. “There is no place in a civilized society, and particularly on a college campus, for urging individuals to harass anyone," Bryant wrote on Twitter.