How (not) to portray a serial killer: Girl with the Dragon Tattoo

Despite its higher ambitions, "The Girl with the Dragon Tattoo," by the end of the 3rd (of 4) sections, has become a search for a sadistic serial killer. Setting aside all my qualms about even the remote likelihood that a madman as Stieg Larsson describes him could get away with a series of such gruesome crimes undetected, there is nothing remotely interesting about this aspect of the novel. Works about serial killers (my references are mostly to films because I don't often read this kind of fiction) can be totally engrossing and fascinating so long as we learn something about how their minds work and how or why they became so deranged (Silence of the Lambs, It, Psycho, Sweeney Todd, to cite 4 very different examples). Or, for an alternative approach, this story line can work if we follow the complex process through which smart cops or detectives unravel the mystery of the killer, often putting themselves in danger during the process. In Dragon Tattoo, neither happens. The killer of course has to be a member of the Vanger family, one of the family members living on the island of Hedeby, where Blomkvist and Salander are investigating a murder or disappearance from 38 years back. When we learn that the killer is Martin Vanger, are we surprised? Do we care? No, that only works if we've gotten to know and see Martin - but he's a character we barely know at all. If a serial killer is to be a minor player in the novel until his secret is revealed, the writer has to present him (or her, for that matter) as either just slightly strange and deranged so we always feel creepy around him or as seemingly very normal - but we gradually learn more unsettling things about them. Either we can know much more than the protagonist (cop or detective) or we see the pieces come slowly into place through the protagonist's POV (which is how Larsson plays it). But what payoff do we get by learning that Martin is a killer? We know it has to be someone on the island, and frankly it might as well be anyone. (Larsson populates the island with unreconstructed Nazi sympathizers, but that's more or less a red herring - they're hateful in other ways). There is no shock of recognition or surprise when Martin is revealed and imprisons Blomkvist in his - ready? - torture chamber that nobody had ever seen or suspected on this tiny island! Though Dragon Tattoo has a veneer of social significance - references to violence against women, to neo-Nazis (which Larsson apparently bravely pursued during his own heroic life cut too short), the story itself is more about random, crackpot violence and, to be frank, authorial manipulation.