John R. Lott Jr., the controversial economist whose work is celebrated by the National Rifle Association and other pro-gun groups, will take part in the second meeting of President Donald Trump’s “election integrity” commission.

Lott will appear as the final witness in the first panel during Tuesday’s meeting, on the subject of “Historical Election Turnout Statistics and the Effects of Election Integrity Issues on Voter Confidence,” according to a report by Talking Points Memo. Other witnesses include Andrew Smith, a professor of political science at the University of New Hampshire, and Kimball Brace, who heads Election Data Services, a consulting firm.

Trump founded the commission in May after falsely claiming that millions of Americans voted illegally in the 2016 presidential election.

Lott is the founder and president of the Crime Prevention Research Center, a nonprofit which regularly publishes stats-heavy articles and blog posts with a pro-gun bent. Ted Nugent and former Milwaukee County Sheriff David Clarke, both prominent NRA supporters, serve on the organization’s board of directors.

Lott rose to prominence in the gun-rights world after the 1998 publication of his book More Guns, Less Crime, which argued that firearms deter violence. Gun-rights groups were quick to embrace Lott’s viewpoint. He remains a fixture at the NRA convention and a frequent contributor to conservative outlets such as Fox News and The Daily Caller. Lott is often also called to testify before state legislatures in support of bills expanding gun carry to more public spaces.

But as Lott’s work became the backbone of many pro-gun arguments, it came under scrutiny from respected academics:

The National Research Council, a branch of the National Academy of Sciences, assembled a panel to look into the impact of concealed-carry laws; 15 of 16 panel members concluded that the existing research, including Lott’s, provided “no credible evidence” that right-to-carry laws had any effect on violent crime. Economists Ian Ayres of Yale University and John Donohue of Stanford University argued that Lott had drawn inaccurate correlations: Cities had experienced a spike in crime in the 80’s and 90’s in part because of the crack epidemic, not because of strict gun laws. When they extended their survey by five years, they found that more guns were linked to more crime, with right-to-carry states showing an eight percent increase in aggravated assault. Mother Jones

Earlier this year, Donohue, the Stanford professor, published a comprehensive rebuke of Lott’s central thesis that guns contribute to public safety. Authors Evan DeFilippis and Devin Hughes have published several articles on The Trace directly debunking research conducted by Lott and his team at the Crime Prevention Research Center.

Numerous other outlets, and even conservative researchers, have detailed issues with Lott’s work, and questioned why some media organizations continue to repeat his findings.

So why is Lott appearing on a panel that has nothing to do with guns? As examples surfaced by Talking Points Memo show, his work sometimes branches out to address other conservative causes: Here’s a blog post, arguing that the 2016 North Carolina gubernatorial election was the subject of absentee ballot voter fraud, and a Fox News op-ed suggesting that felons voting illegally were responsible for the 2008 election of Senator Al Franken.