The group of 467 former "Jeopardy!" contestants issued an open letter Wednesday, demanding "a statement and a disavowal" of the actions of Kelly Donohue ... who it accuses of racist messaging "either intentionally or unintentionally" on 2 separate occasions this week.

According to the letter, posted on Medium, the most egregious incident happened Tuesday, when Donohue made a 3-finger gesture to the camera that's extremely similar to the gesture "co-opted by white power groups, alt-right groups, and an anti-government group that calls itself the Three Percenters."

Donahue insists his hand signal was simply to indicate he'd won 3 games. In fact, Thursday morning he posted a long response to the backlash, saying, "I deeply regret this terrible misunderstanding. I never meant to hurt a soul and I assure you I am no friend of racists or white supremacists."

Even if that's true, the past players are still pissed "Jeopardy!" allowed the gesture to air without censoring it, and they point to a past example.

"A couple of years ago, a contestant unintentionally wagered a monetary amount that used numerical values coopted by white supremacist groups and, since the total didn’t affect the outcome of the game, 'Jeopardy!' digitally altered the numbers in the version that aired."

It should also be noted that Donahue held up one and two fingers after his first and second wins ... seemingly supporting his explanation that there was no hate behind it.

Even so, the former contestants believe it was on the production team to similarly catch Donohue's gesture and make an edit. The letter also alleges Kelly responded to a clue on Monday with a term for the Romani culture that's considered a slur.