Writer-director David Jacobson’s creepy biopic of serial killer Jeffrey Dahmer seemed an unlikely candidate for success.The subject matter scared agents from submitting the “Dahmer” script to clients. Film distribs passed. Major festivals rejected it. And when producer Larry Rattner’s distrib arm, Peninsula Films, self-released the pic in 16 cities last summer (grossing around $200,000), some moviegoers criticized it for not being gory enough. “From the very start, I had so many people telling me don’t go there,” says Jacobson, who forged ahead anyway, initially backing the film with his own coin. (Pic was shot for $225,000 and finished for less than $500,000 with help from video distrib DEJ Prods.) But “Dahmer” did get a break when critics responded positively to the film’s non-exploitative take, its polished look and evocative performances. Plus vid rentals are solid. Now, thanks to its three Spirit Award nods — in addition to the Cassavetes nom, it’s also up for actor (Jeremy Renner) and debut performance (Artel Kayaru) — “Dahmer” is finally gaining credibility and finding its intended aud, the art house crowd.