An interview and an interrogation serve very different purposes, so treat them differently. An interview should last no more than 20 or 30 minutes, the length of the average person’s keen attention span. An interrogation on the other hand goes as long as is necessary, presenting your evidence and coaxing a confession from the subject. Mixing interviewing with interrogation with interrogation is a common mistake even among seasoned law enforcement professionals, says Nathan Gordon, coauthor of Effective Interviewing and Interrogation Techniques,.”]
Source: https://www.csoonline.com/article/2118813/how-to-spot-a-liar–identifying-deceptive-behavior.html