How to test for malingering in criminals trying to deny capacity for criminal responsibility? Psychiatrists and psychologists are often tasked with assessing a criminal defendant's competency to stand trial or his capacity for criminal responsibility. What objective tests are useful for assessing whether the person is malingering or faking symptoms to appear not competent to stand trial or not guilty by reason of insanity?

I am a prosecutor in the US. We are getting more cases where the defendant's competency to stand trial is called into question by defense counsel. Many of the forensic examiners are concluding that defendants are not competent without seeming to use objective measures to rule out malingering.
More comprehensive ones than the abovementioned memory test include the Miller Forensic Assessement of Symptoms and the Structured Interview of Reported Symptoms. These assess a wide variety of psychiatric symptoms and are supposedly very hard to fake.