Why did Stalin bother with trials for his victims?
I mean, it's not as if he was fooling anyone, so why didn't he do like Hitler and just murder his victims without the sham trials? He just doesn't seem like the guy who would be concerned about public image.
It's a great question. First, let's remember that Stalin was not a normal person by any stretch of the imagination, so his logic and line of thinking don't follow what we would expect as normal human behavior. Since his actions are difficult to understand outside the context of his sociopathy, any guess we might make as to his real motivations are difficult at best. I have two theories in answer to your question.
1) Stalin's purges and deportations were an exercise in control. He was consolidating his power over a vast and diverse populace. So the trials, while a sham that very few people were buying, were a necessary facade, to Stalin anyway, in order to prop up his legitimacy in the eyes of mainstream Soviets.
2) In order to perpetrate such genocidal acts, Stalin had to, on some bizaare and insane level, convince himself of the justice of his orders. In this way, perhaps the trials weren't for the public at all, but for Stalin and those party elites that needed to believe in what they were doing in order to do it at all.