subgenre began as literal adaptations of the original giallo mystery novels (see Giallo (1933 film)). Directors soon began taking advantage of modern cinematic techniques to create a unique genre that retained the mystery and crime fiction elements of giallo novels but veered more closely into the psychological thriller or psychological horror genres. Many of the typical characteristics of these films were incorporated into the later American slasher genre. Characteristics Most critics agree that the giallo represents a distinct category with unique features, but there is some disagreement on what exactly defines a giallo film. Gary Needham wrote: <blockquote>By its very nature, the giallo challenges our assumptions about how non-Hollywood films should be classified, going beyond the sort of Anglo-American taxonomic imaginary that "fixes" genre both in film criticism and the film industry in order to designate something specific. ...however, despite the giallo'''s resistance to clear definition, there are nevertheless identifiable thematic and stylistic tropes.</blockquote> These distinct "thematic and stylistic tropes" constitute a loose definition of the genre which is broadly consistent, though various critics have proposed slightly differing characteristic details (which consequently creates some confusion over which films can be considered gialli). Author Michael Mackenzie has written that gialli can be divided into the male-focused m. gialli, which usually sees a male outsider witness a murder and become the target of the killer when he attempts to solve the crime; and f. gialli, which features a female protagonist who is embroiled in a more sexual and psychological story, typically focusing on her sexuality, psyche and fragile mental state. Although they often involve crime and detective work, gialli should not be confused with the other popular Italian crime genre of the 1970s, the poliziotteschi, which includes more action-oriented films about violent law enforcement officers (largely influenced by gritty American films such as Bullitt, Dirty Harry, Death Wish, The Godfather, Serpico, and The French Connection). Directors and actors often moved between both genres and there is some overlap between them. While most poliziotteschi dealt with organized crime and police responses to it, some early examples of the genre focused instead on murder investigations, and especially on cases where a woman had been murdered in sexual circumstances. These films were more psychological than action-driven, and borrowed various themes and motifs from gialli. Examples include Investigation of a Citizen Above Suspicion (1970) and No, the Case Is Happily Resolved (1973). Some films could even