Capgras syndrome is a part of the delusional misidentification syndromes. In this condition, the patient believes that identical individuals have impersonated the people close to them, leading to aggression or even homicide of their relatives. The following article describes the case of a 28-year-old patient with a history of cannabis consumption who arrived at the emergency department due to an unsuccessful murder attempt against his neighbor. At the mental examination, the patient believed their parents were killed some time ago, and impostors were replacing them; laboratory tests showed tetrahydrocannabinol in the urine sample. Therefore, the diagnosis of Capgras syndrome due to cannabis consumption was performed, and treatment was established with two antipsychotics and one mood stabilizer drug, showing satisfactory results after two months.