The Cat o' Nine Tails (1971)
A reporter and a blind, retired journalist try to solve a series of murders. The crimes are connected to experiments by a pharmaceutical company in secret research. The two end up becoming targets of the killer. psychopath, adoption, stalker, murder, laboratory, homicidal, serial killer, slasher, whodunit, maniac, psychiatrist, policeman, mental illness, psycho killer, child kidnapping, multiple murder, voyeurism, madman, blind man, giallo