There is increasing demand for psychiatric expert testimony in criminal proceedings. A person is responsible for his actions unless he is subject to the penal code, Section 34 h, insanity. Mental illness is not sufficient to determine insanity; it must be proven that the patient did not understand what he had done, did not comprehend the inappropriateness of his actions: or could not have avoided performing the deed. Opponents argue that the expert testimony is not scientific and not professional and alternatively that the mentally ill avoid responsibility even when there is no connection between the illness and the offense.

The polygraph examination is an important instrument for confirming credibility of the testimony but it has not yet been investigated in the field of forensic psychiatry.

To examine the validity of a polygraph examination in psychotic patients. To compare polygraph tests with psychiatric examinations.

Patients were tested with a polygraph examination on there misjudged psychotic behavior.

24 patients signed a consent form, but not all eventually participated. all patients received antipsychotic medications. in general valid polygraph examination can be performed to patients with the psychotic illnesses (i.e. schizophrenia). Agitated or cognitive deprived patients tests were not reliable. the psychiatric examinations or the expert testimonies were in accord with the polygraph examination.

Preliminary data indicate that polygraph examinations are valid in patients with the psychotic illnesses. But not in agitated or cognitive deprived patients. Expert testimonies were found reliable in determining insanity.