From the Life of the Marionettes

Peter kills Ka when she reveals her real name is Katarina, the same as his wife. This triggers an emotional blackout because Ka represents a mirror of his wife, combining his desires and fears into one person. The name revelation disrupts his psychological state, causing him to lash out violently in a moment of overwhelming emotion.

Earlier, Peter confided to Jensen about homicidal thoughts toward his wife Katarina, hinting at his unstable mental state.

Peter confides in Mogens Jensen because he is in severe psychological distress and cannot cope with his intrusive thoughts alone. Jensen is his close friend, and Peter likely hoped for understanding or help. This confession shocks Jensen, who later advises Katarina to leave town as a precaution.

The confession foreshadows the actual murder, showing Peter's thoughts had progressed from fantasy to intent.

Katarina dismisses the warning because she views it as impractical and exaggerated. She cites her demanding work schedule and the impossibility of leaving during a busy season. This reflects her character, independent, career-focused, and perhaps in denial about the severity of Peter's psychological state.

Katarina's dismissiveness contrasts with the tragic outcome, showing how warnings went unheeded.

Tim feels guilty because he introduced Peter to Ka as part of his plan to seduce Peter into an affair. Tim is homosexual and desired Peter, so he arranged the meeting thinking it would draw Peter toward him. Instead, the encounter led to Ka's murder, making Tim blame himself for causing the tragedy.

Tim hesitates when interrogated about his relationship with Peter, hinting at his hidden motives.

Peter's suicidal thoughts stem from his deep psychological crisis, his inability to reconcile his desires, his violent impulses, and his failing marriage. He considers jumping from a building but is interrupted when Katarina calls a friend to help calm him. This moment shows Peter's fragile mental state before the murder.

The suicide attempt reveals Peter's desperation and sets up his later violent outburst.

Peter is institutionalized because the murder and necrophilia were deemed results of his psychological collapse. The film ends with him clutching a teddy bear at night, symbolizing his return to a childlike, vulnerable state and his complete inability to cope with what he has become.

The institutionalized ending reflects the psychological deterioration shown throughout the film.

Mogens Jensen explains that Peter, shaped by an aggressive mother and then living with an aggressive wife, did not recognize his own repressed homosexuality. Meeting Ka disrupts his carefully maintained routine, and when Ka reveals her name is Katarina, the shock triggers an emotional blackout he cannot recover from, leading to the murder.

Peter's tense relationship with both his mother and wife has been established throughout the film.

The open marriage fails because Peter cannot handle the sexual freedom Katarina desires. While she openly discusses having orgasms, faking them, and leaving to masturbate, Peter feels inadequate and threatened. His insecurity and desire to be the one who satisfies her clash with her independence, creating resentment and deepening his psychological crisis.

The couple's arguments about their open relationship highlight Peter's insecurities before the murder.

The teddy bear symbolizes Peter's psychological regression to childhood helplessness. After committing the murder and facing the consequences, he is reduced to clutching a teddy bear at night, an image of vulnerability and complete mental collapse, reinforcing the film's bleak tone about the fragility of the human psyche.

The teddy bear appears in the final scene, capping Peter's descent into isolation.

Ka sharing the name Katarina, identical to Peter's wife, forces him to confront the merging of his desires and fears. She represents both his sexual attraction and his violent impulses toward his wife. The coincidence shatters his fragile psychological barriers, triggering the violent act.

The name revelation is explicitly mentioned as the moment that causes Peter to kill Ka.