A professor who gained notoriety by questioning whether the elementary school massacre in Newtown, Conn., and other bloody crimes were hoaxes perpetrated by the government has sued a Florida university for firing him, saying that he was targeted for exercising his right to free speech.

The professor, James Tracy, filed suit on Monday in Federal District Court against Florida Atlantic University, where he taught for 13 years, and United Faculty of Florida, the union that had represented him.

The university, a state institution based in Boca Raton, dismissed Mr. Tracy in January from his tenured position as an associate professor of communications for failing to submit forms documenting the work he did outside the university.

It was that work, writing for an alternative news site and for his blog, that drew attention to Mr. Tracy and led to pressure to oust him after the Dec. 14, 2012, shooting at Sandy Hook Elementary School, in which 20 first graders and six adults were killed.