Only interrogations of a person who is in custody are subject to Miranda. As long as the circumstances do not amount to a formal arrest or its functional equivalent, there is no need to give Miranda admonitions before questioning. (Berkemer v. McCarty) When you ask a suspect to come to the police station voluntarily for questioning, there is no need to give Miranda warnings, as long as you make clear that the person is not under arrest and is free to leave at any time.
Jerry Lain Beheler was a suspected accomplice in a drug rip-off murder when he agreed to go to the station for questioning. He was told he was not under arrest, and he was treated accordingly throughout the interrogation (no cuffs, no shackles, no locked doors, no restraints on his ability to leave the station whenever he wanted). Even though his resulting confession was not preceded by Miranda warnings, the U.S. Supreme Court held that his statements were admissible.
Quoting from an earlier opinion on the same issue, the court said the following: "Miranda warnings are not required simply because the questioning takes place in the station house, or because the questioned person is one whom the police suspect."
Where the suspect is not considered a flight or safety risk, officers have the option of asking an unarrested suspect to come in for questioning, and to use what has come to be known as a "Beheler warning," as follows: "You're not under arrest. You're free to leave here whenever you want." (It's important not to create due process problems by telling the suspect he is not going to be arrested, or that he will be free to leave after questioning. The Beheler admonition should be kept in the present tense, as set forth above.)
The Fields Admonition