These are depicting Russian Matryoshka dolls - a set of wooden dolls of decreasing size placed one inside the other. The artist is signifying the "matryoshka principle" or "nested doll principle". It denotes a recognizable relationship of "object-within-similar-object" such as an onion - If the outer layer is peeled off an onion, a similar onion exists within. In the above case the artist is showing that the politician, ganster and cop are of the same kind. The size of the doll may be portraying their social status. It could also mean that the politician is protected by the gangster who is protected by the dirty cop.