Kris Goldsmith’s campaign to get Facebook Inc. to close fake accounts targeting U.S. veterans started with a simple search.

He was seeking last year to gauge the popularity of the Facebook page for his employer, Vietnam Veterans of America. The first listing was an impostor account called “Vietnam Vets of America” that had stolen his group’s logo and had more than twice as many followers.

Mr. Goldsmith, a 33-year-old Army veteran, sent Facebook what he thought was a straightforward request to take down the bogus page. At first, Facebook told him to try to work it out with the authors of the fake page, whom he was never able to track down. Then, after two months, Facebook deleted it.

The experience launched him on a hunt for other suspicious Facebook pages that target military personnel and veterans by using patriotic messages and fomenting political divisions. It has become a full-time job.

Working from offices, coffee shops, and his apartment, he has cataloged and flagged to Facebook about 100 questionable pages that have millions of followers. He sits for hours and clicks links, keeping extensive notes and compiling elaborate spreadsheets on how pages are interconnected, and tracing them back, when possible, to roots in Russia, Eastern Europe or the Middle East.

FACEBOOK TO BAN VOTING MISINFORMATION AS MIDTERM ELECTIONS APPROACH

“The more I look, the more patterns I see,” he said.

Facebook’s response to his work has been tepid, he said. Company officials initially refused to talk with him, so he used a personal contact at Facebook to share his findings. Lately, the company has been more active.

Facebook didn’t respond directly to a list of questions about Mr. Goldsmith’s research, but a spokesman said the company had 14,000 people working on security and safety—double the amount last year—and a goal of expanding that team to 20,000 by next year.

In a statement, the spokesman said the company relied on “a combination of automated detection systems, as well as reports from the community, to help identify suspicious activity on the platform and ensure compliance with our policies.”

About two dozen of the pages Mr. Goldsmith flagged, with a combined following of some 20 million, have been deleted, often coinciding with Facebook’s purges of Russian- and Iranian-linked disinformation pages—including a separate crackdown by the company last week on domestic actors.

FACEBOOK POSTS MAY REVEAL YOUR DEPRESSION, STUDY SAYS

The most recent suspensions included the page “Vets Before Illegals,” with nearly 1.4 million followers, which Mr. Goldsmith’s research showed had five page administrators in the U.S. as well as three in the Philippines, and DcGazette, a page pushing conservative news that had attracted more than 400,000 followers.

Several of the pages Mr. Goldsmith has studied expressly catered to conservative audiences and frequently promoted divisive memes depicting President Trump favorably on issues involving veterans, illegal immigration and the National Football League. While posts didn’t specifically discuss congressional candidates seeking election in next month’s midterms, they often promoted Mr. Trump’s 2020 re-election bid while disparaging Hillary Clinton as a criminal who deserved jail time.

Click here for more from The Wall Street Journal, where this article originally appeared.