It does not matter where the interrogation of a suspect occurs, whether it was at the police station, at the crime scene, or in the middle of a public area. This is why police officers are required by law to read the Miranda rights to any individual accused of a crime, if they want to ask the suspect questions, and use the responses as credible evidence in court. On the other hand, if the person of interest is not under arrest, the Miranda rights are not required and anything said can be used against them at trial. I think this is mainly why police officers would most likely avoid arresting someone, and clearly stating that he/she is free to go at any time during police questioning, specifically so they do not have to read the Miranda rights. That way, the police can arrest the person of interest after getting the incriminating evidence or statements they were hoping for all