Best Investigation movies of 1970s

Actors : Evert Anderson, Anja Schmidt, Kelvin Malave, Thommy Berggren,
Directors : Bo Widerberg,

About the life and death of the legendary Swedish/American agitator Joe Hill.

Actors : Bryant Haliday, Jill Haworth, Mark Edwards, Jack Watson,
Directors : Jim O'Connolly,

A group of experienced archeologists are searching for an old and mystic Phoenician treasure when they are surprised by a series of mysterious murders...

Actors : Ryouko Ima, Yayoi Watanabe, Yumi Takigawa, Emiko Yamauchi,
Directors : Noribumi Suzuki,

In order to investigate her mother's strange death, a woman enters a sacred convent run by hypocritical, perverse nuns.

Actors : Franco Fabrizi, Giovanna Ralli, Claudio Cassinelli, Mario Adorf,
Directors : Massimo Dallamano,

Police investigate apparent suicide of teen girl and uncover details of a teenage prostitution racket. They go on the hunt for a motorcycle riding killer.

Actors : Hector Elizondo, Susan Blakely, Michael Moriarty, Yaphet Kotto,
Directors : Milton Katselas,

Police officer Patty Butler, alias "Chicklet," is the live-in girlfriend of Thomas 'Stick' Henderson to gather evidence. Detective Bo Lockley is instructed to try to find her, not knowing she's also a cop.

Actors : María Kosty, Víctor Petit, Sandra Mozarowsky, José Antonio Calvo,
Directors : Amando de Ossorio,

In this final installment of the Blind Dead series, a doctor and his wife move to a small inhospitable coastal village where he plans to start a practice only to discover that undead demon-worshiping Templar Knights haunt the place.

Actors : François Périer, Stefania Sandrelli, Simone Signoret, Yves Montand,
Directors : Alain Corneau,

An inspector is having a secret relationship with a woman. When she is murdered by his boss, all proof is against him.

Actors : Steve Vincent, John F. Goff, Douglas Gudbye, Verkina Flower,
Directors : Stu Segall,

Two police detectives try to catch a serial killer who is stalking a rural California drive-in theater, randomly killing people with a sword.

Actors : Andreas Mannkopff, Klaus Kinski, Josephine Chaplin, Herbert Fux,
Directors : Jesús Franco,

A serial killer whose mother was a prostitute starts killing streetwalkers as a way of paying back his mother for her abuse.

Actors : Roger Davis, Stuart Whitman, Janit Baldwin, Piper Laurie,
Directors : Curtis Harrington,

Sixteen years after Ruby Claire's gangster boyfriend was shot and killed by four associates, a series of gruesome murders takes place at the drive-in movie theatre she now owns. Meanwhile, ...

Actors : Barbara Steele, Cameron Mitchell, Avery Schreiber, Rebecca Balding,
Directors : Denny Harris,

During her first semester at college, a co-ed finds housing at a seaside mansion where, following the death of a fellow-student, she becomes entangled in a murder mystery surrounding the property and it's secretive tenants.

Actors : James Westmoreland, Nicholas Worth, Ben Frank, Flo Lawrence,
Directors : Robert Hammer,

A deeply disturbed Vietnam veteran terrorizes the young women of Los Angeles and taunts a radio psychologist with descriptions of his grisly crimes.

Actors : Barbara Babcock, Harry Dean Stanton, Paula Prentiss, Robert Foxworth,
Directors : Harold Becker,

A romantic comedy which explores the pressures on police officers.

Actors : Ângelo Assunção, Ronaldo Beibe, Andreia Bryan, José Mojica Marins,
Directors : José Mojica Marins,

Psychiatrist experiments LSD on 4 volunteers, to investigate Coffin Joe's influence over them. Each patient presents a different reaction, involving sex, perversion and sadism.

Actors : Shane Briant, Yvonne Mitchell, Robert Hardy, Gillian Hills,
Directors : Peter Sykes,

A physician discovers that two children are being kept virtually imprisoned in their house by their father. He investigates, and discovers a web of sex, incest and satanic possession.

Actors : Carmen Young, Rita Calderoni, Mickey Hargitay, Raul Lovecchio,
Directors : Renato Polselli,

A respected doctor becomes the prime suspect in a series of gruesome murders.

Actors : Kurt Raab, Jeff Roden, Margit Carstensen, Ingrid Caven,
Directors : Ulli Lommel,

Story of a gay serial killer who murders young boys so he can serve them as dinner to his circle of fellow cannibals.

Actors : Cristina Galbó, George Hilton, Antoine Saint-John, Femi Benussi,
Directors : Luigi Cozzi,

Giorgio is a greedy adulterer who makes a deal with a serial killer to dispose of his wealthy wife, Nora. Unfortunately, a thrill-seeking young couple steal the killer's car with Nora's ...

Actors : Mimsy Farmer, Ray Lovelock, Barry Primus, Carlo Cattaneo,
Directors : Armando Crispino,

A pathology med student and a priest team up to investigate a wave of suicides blamed on sun spots and discover a number of them to be actual murders.

Actors : Shirley Washington, Trina Parks, Edna Richardson, Bettye Sweet,
Directors : William Witney,

Syreena must investigate the disappearance of her mother, Cinderella. A series of wild complications follow.