Here are some known facts:
The Constitution applies to US Citizens.
The Constitution includes the Bill of Rights.
The Bill of Rights are the first 10 Amendments.
One of those Amendments is the 5th Amendment.
The 5th Amendment provides for Due Process.
Due Process applies to US Citizens.
Now let's define due process. In a nutshell, due process is presenting your case in court fairly.
There are two types of due process: substantive and procedural.
Substantive due process: whether the government has an adequate reason for taking away a person’s life, liberty, or property.
Procedural due process: the procedures a government must follow to take away someone’s life, liberty or property.
Yes, we just defined due process but now it gets a teensy bit tricky.
When police take a person into custody and interrogate him (custodial interrogation), that person must be given Miranda warnings regardless of the severity of the crime.
This is where people start citing the "Public Safety Exception". This exception allows police to question a suspect in custody without Miranda warnings about the location of a missing gun or the location of a missing kidnapped victim for the protection of the police or the public. These are immediate questions for a perceived immediate threat.