In 'Strangers on a Train', what object does Bruno use to frame Guy?

In Strangers on a Train, Bruno uses a cigarette lighter to frame Guy for Miriam’s murder.

Guy leaves behind his engraved lighter after meeting Bruno on the train. Bruno later plans to plant it at the murder scene, creating physical evidence that could suggest Guy was present and involved. Guy realizes the danger when Bruno mentions the missing lighter to Anne.

The lighter becomes an important object in the film’s final sequence at the amusement park. During the chaotic carousel confrontation, Bruno dies clutching it, and his fingers eventually reveal the lighter to the police. Its engraved surface links it directly to Guy, but the discovery also helps expose Bruno’s scheme rather than convict Guy.

The lighter is easy to confuse with the pistol, house key, or map Bruno sends to Guy later. Those objects are part of Bruno’s coercive plan, but the cigarette lighter is the item intended to implicate Guy at the crime scene.