John Landrysmith was hired at the memorial in 2012, where he helped guide visitors and manned the ticket booths.
But less than a year into the job, he complained to federal investigators that hundreds of tickets that were supposed to be available to the public for free were being diverted every day to tour companies.
"You would have tour drivers with handfuls of tickets … ‘oh how many you got, whatever.’ And at the same time, I'm in a ranger uniform standing behind the desk with no tickets saying, 'Folks, I have nothing for you,'" he said.
Based on his tip, federal investigators later found that the tour companies were selling those tickets for $39 to $89.
Last week, authorities confirmed the companies were providing improper gifts to a staffer.
Although charges were never filed, the National Park Service said it has since implemented reforms.
Ticketing decisions are now handled by a team of employees and not a single staffer, it said. And all employees now have to undergo ethics training.
But investigators apparently didn't address the retaliation against Landrysmith, who raised the issue.
"It was absolutely personal and absolutely directed retaliation against me," he said. "Not only did I get a verbal warning, my schedule was changed. I was denied (family leave)."
Landrysmith said he found another job after he was told he wouldn’t be retained.
He later filed a wrongful termination lawsuit. With the help of attorneys Richard Gronna and Michael Green, the suit was quietly settled, with the Park Service paying him a year's salary.