This depends on how hard the government works to hide things. If the only thing the government does is say "this was not a crime" then no. Books and literature and histories and historians will remember the events because humanity doesn't really 'forget' about anything. Unless the government explicitly bans discussing it the knowledge of the event will continue to be maintained.
For that matter a good part of China is fully aware of Tienanmen square despite China's doing everything they can to erase it. That was only a quarter century ago, but the point is that it's hard to erase knowledge. If you try too hard to erase details they will become a rally call that everyone remembers in order to spite your control.
I think the key difference between your question and the psychology you mention is the word "forget". The event can't be forgotten easily. However, people can be convinced to forget that it was an atrocity. It can be whitewashed and remembered more forgiving then it really was. The facts are known, but the cultural memory of the event is not one of an atrocity. Some may look up the actual facts from history books and say "you know, that really was a lot worse then I had been taught", but most won't bother to do so. 95% of society will remember things as justified and right at the time, as they have been told and taught.
It's possible that the public as a whole would be so indoctrinated that even if someone came to them and said "look, here are the facts of what happened, see how horrible it is" the average person will still argue blindly that it was not horrible at all. They may ignore the facts, refuse to believe them despite those facts being clearly recorded historical works, or claim that the provider of the facts is exaggerating them and/or ignoring other details that made it 'justified'. In short once you're taught something is right for long enough you resist any argument to the opposite, even in the face of logic.
It's therefore possible for the public memory of an event to be wiped out, even when the actual facts and details being clearly recorded. Some may have realized the truth after taking the time to learn the actual facts, but the majority of the population can be kept in their utopian idea of everything being perfect and wonderful while being ignorant of facts that are right under their noses. Somehow I think it makes a story even better to have the knowledge easily available and yet still ignored, and it makes it easier to have some dissenters without them needing to stumble upon a mass grave or some other deep-dark-secret to do so; they're simply the ones who were unbiased enough to research the raw facts and come to a proper conclusion.
To give you an example of how the public memory can be adjusted consider this scenario:
You're trying to colonize lands and having trouble defending them from the indigenous people and other colonizing countries. Your government puts in a massive expense to protect and defend you from those indigenous people, costing it massively. After protecting you the government realizes it suffered so heavily in doing so that it can't afford to cover it's other expenses, so it asks you to help repay some of the cost spent to defend you. In response to being asked to pay for your own defense, via taxes placed only on non-mandatory luxury goods that will not harm those who truly can't afford them, you protest by destroying a third-party's cargo of supplies without repaying them while trying to place blame for it on the indigenous people. Then you start a war that kills over 50,000 and strikes a blow to your home country that will cause it to suffer many other losses in future decades.
Welcome to the US revolutionary war, which those of us in the US are all taught was 100% justified and right and totally-not-at-all-selfish-waste-of-life-to-avoid-repaying-or-own-debts!
Now I admit I may be exaggerating the situation above to make a point, since most of the real atrocities of the US are recognized as such so I had to settle for more of a moral grey area. However, my point still stands. Even though we know all the actual facts of the war, anyone can look them up any time, if you ask the US people no one will consider any nuance beyond "we were being controlled and had to be independent". We are told it was justified, and so that's what we accept, no one even bothers to look up history or wonder about any complexity. To repeat I am not claiming that the war was a clear atrocity or wrong, only that discussion of it as anything other then purely 100% just seems limited by our education and dogma.
This is also, by no means, limited to the US or this one war. Look at any war your country (any country) fought and the schools will teach it as completely just, and that you were the most important factor in winning the war; oh and you clearly 'won' even if other side claims they were the ones to win. The World wars are unique in that WW2 is kind of believed that the allies were 'in the right' in most places, Hitler was just so wrong that even Germany doesn't try to treat him as a hero. Still, a certain degree of whitewashing of history happens in every countries education system, usually not to the extreme of hiding atrocities, but perhaps removing the 'grey' of more ambiguous situations, and for the most part their citizens accept these 'facts' as truth despite the easy of getting the actual historical details.
Out of curiosity I ended up Googling what England taught about the revolutionary war, to see if they taught it as us horrible US folks wanting to have our tea and drink it too. Turns out that England barely covers the war in their classes. Partially because it's merely one of many colony upraises (admittedly the first major one), and as such gets thrown into a general time period of unrest rather then being singled out, partially because it simply wasn't as critical a battle for them and they don't have time to cover wars that aren't imperative to their history, and partially because it looks like many countries tend to focus far less time on studying wars which they 'lost'. Not relevant to the question, but interesting to me non the less :)