It's technically an anarchist thing but socialists in capitalist countries aren't going to be pedants about that. Just like many of the things anarchists say after "abolish" (police, prisons, the state, etc.) socialists see police in service of the dictatorship of the proletariat as useful or necessary. However, we also think the method of policing and the crimes policed would be drastically different between a socialist and a capitalist society. We remold the state apparatus to fit the needs of the dictatorship of the proletariat just as the bourgeoisie molded the old feudal state to their needs.

Edit: The hope is that eventually they aren't necessary though like all parts of the state apparatus. That's in the future though and there's not really any way to describe the evolutionary process to that besides "the withering away of the state".