Guilty knowledge test or Concealed Information Test is only done between the police and the perpetrator of the crime.
Explanation:
It is a questioning technique used to assess the suspect’ ability to conceal guilty knowledge of the crime. It can be used along with the polygraph test and it tests the suspect’s physiological responses during the question session. The questions asked are multiple-choice questions which do not reveal much information about the crime investigated.
It is believed that based on their response, innocent suspects find all the provided options plausible. Guilty suspects, however, will know the correct answers. The polygraph examiner takes note of the physiological cues or arousal as each option is presented.