A remarkable procedural thriller. The movie is consistently strong throughout, featuring a superb cast. George Kennedy and Henry Fonda are particularly effective as the detectives tracking down the perpetrator, conveying both frustration and disgust with considerable skill. However, Tony Curtis truly carries the film, appearing significantly altered in physique from his usual image. He’s convincingly threatening and navigates the scenes depicting his character's fractured personality with great care. A significant strength is that for its initial sixty minutes, the movie only presents the consequences of the murders, illustrating the intense fear they inspire in Boston’s residents and allowing us to become acquainted with the investigators on the case. Around the midpoint, Tony Curtis appears as Albert De Salvo, depicted within his family setting—a brilliant choice by director Richard Fleischer that maximizes the emotional effect. The clever use of multiple screens to display different facets of scenes adds a sense of realism, which is amplified given the film’s basis in true events. It's a genuinely powerful movie that lingers in your thoughts long after the closing credits. 9/10

Source on TMDB