Sadly, we will never know if he asked the interrogation, after 8 hours to cease, but if you think about it in all likelihood anyone would want to stop after 8 hours come on guys!
US Supreme Court rules that confessions obtained after six hours by federal investigators may not be admissible
In order to prevent misconstruction or abuse of its powers
Unreasonable searches and seizures
Probable cause, supported by Oath or affirmation
Nor shall be compelled in any criminal case to be a witness against himself,
To be confronted with the witnesses against him
Without due process of law
Deny to any person within its jurisdiction the equal protection of the laws.
As far as interviewing goes if you are not arrested they have a reasonable amount of time to talk to you and get identification Information.
You're free to leave at any point during an interrogation.
Once you're in custody that's a different story.
You're not obligated to go questioning it's your choice unless they have a court order.
A very long interrogation may lead to a ruling that the confession was involuntary (and thus unreliable)
http://answers.yahoo.com/question/index?qid=20090513111034AAT9M3 this is called the right of silence you have no legal duty to answer any question, and you may refuse to answer.
.This is called the right of silence
A person is stopped, or detained, when an officer uses enough force, or a show of authority, to make a reasonable person feel he or she is not free to leave.
https://www.ohiobar.org/ForPublic/Resources/LawFactsPamphlets/Pages/LawFactsPamphlet-21.aspx
The recalcitrant subject of an intelligence interrogation must be "broken" but broken for use like a riding horse, not smashed in the search for a single golden egg.
Since statements by the accused may be barred as court evidence on the ground that they were made under duress, during prolonged detention without charge,
The interview must of course be recorded, either on tape or in stenographic notes.
When the subject has ceased to resist his interrogators and is ready to talk freely he must be handled with great care, both because this attitude may change and because he may now have suicidal impulses. He should get better treatment and better detention conditions
In this chapter, we review three defining issues related to the interrogation of suspects..... Inappropriate interrogation techniques (e.g., overly long interrogations,
However, the length of the interview
. made for a setting which was not conducive to the taking of a knowing and voluntary statement."
https://www.cia.gov/library/center-...ence/kent-csi/vol2no3/html/v02i3a08p_0001.htm[PDF]
http://reid.com/reid_topics/length.html