Although the cause of schizophrenia is not known, there is strong evidence that its development takes a particular combination of genes passed from one generation to another. However, the biological inheritance must be accompanied by environmental stresses. Symptoms usually become apparent in late adolescence or early adulthood. Three groups of psychotic symptoms are most easily recognized. First, the person's thought content will be delusional. If a law enforcement officer encounters a person in this state, it is best not to argue with him because delusions are a fixed belief and it will only worsen the situation. The second group is known as formal thought disorder, or the disorganization of thought. The response of the officer to these seemingly bizarre statements may be confusion and impatience. The third group are known as hallucinations, which are sensory perceptual experiences, usually auditory, that occur without any external stimulus. The rule of thumb is that most individual schizophrenics, upon arrest, are frightened and compliant. They pose little or no danger to the arresting officer. The officer should handle the field interrogation and arrest in a cautious and firm manner. A psychiatric evaluation should be done prior to booking the individual into custody.