In essence, Andrei's murders are an attempt to recreate a formative childhood experience—the day that was both the best and worst of his life. The easiest way to understand this is by looking at the symbolism of each aspect of the murders:
- The ground-up bark represents the tree bark Andrei chewed to ease his anxiety while he and his brother hunted. This is example of how Andrei looked up to Pavel: after all, it was big bro who "told him bark paste sated feelings of hunger" (1.1.46).
- The string tied around his victims' feet represents the snare he and Pavel used to catch the cat. The only difference is that the child is being hunted for a cat's meal, rather than the other way around.
- Pavel also removes his glasses before the murders, reflecting how he had been too poor to afford glasses back then. Now when he looks at his victims "all he could see was an outline, an indistinct splash of pink skin contrasting with the ground" (3.31.65).
So why is Andrei doing this? Is he really just trying to get his brother to notice him? Leo had actually wondered why "he couldn't stop thinking about" these "incomprehensible details," which certainly lends credence to the idea (3.23.1). Still, it's clear that Andrei gets some sadistic pleasure out of the murders, which implies that he's simply gone mad. Whichever way you land—even somewhere in-between—we can all agree that Andrei's murders are rooted in his childhood trauma.
Andrei's grisly murders also reflect the grisliness of his society. Remember how easy it is for Andrei to escape notice, simply because he looks so normal? Yeah, well, what's normal in this society is murder and deceit. Andrei's childhood trauma reflects the nasty conditions that actually took his brother away from him. The Soviet government doesn't want to acknowledge that these kinds of murders can happen on Soviet soil because in a way, they show that the system itself is totally corrupt.