When setting up an environment for interrogative, the investigator needs to consider the suspect and purpose.
There are different purposes for interrogation, and different suspects. Some suspects an investigator will find very forthcoming and helpful, some evasive, and some frightened. To get the most out of the interrogation, the investigator needs to carefully consider what state of mind the suspect is in.
There are several factors to consider in setting up the environment. First, who will interrogate? Some suspects respond better to me, some to women, some to those they see as authority figures, some they see as subservient, and some they relate to — such as someone who speaks the same language or is the same race or culture.
Second, the physical environment is important. Some suspects will respond well to a cup of coffee, a glass of water, or a snack. Others will prefer being asked what they want, and they might be more forthcoming as they wait or once they get it. Sometimes, withholding food or water can be effective—and even bringing water to make the suspect need to restroom, although that can be abusive and one should be cautious.
You should ask yourself, what will make the suspect talk? Should you bring him a sweatshirt if he is cold? Should you turn the air on, or off? Should you use bright lights or darker rooms? Where do you put the table? The suspect’s chair? Your chair? Which side do you put the suspect on, in relation to the viewing window? Do you cuff the suspect? Should the chair be moveable? Do you bring a comfortable chair, or an uncomfortable? It is all about reading your suspect’s behavior and personality, and trying to determine what will make him talk to you and give you what you want.
When to Mirandize is also important. Sometimes you can get a suspect to waive Miranda if you make it sound like you are just having a conversation. The worst thing that can happen is that he asks for a lawyer, because then the interrogation ends. Yet remember you can’t legally use anything he gives you before his rights have been read.