In colorado v. connelly (1986), scotus considered the case of a mentally ill man who approached an officer on the street and confessed he had murdered a young woman. the court determined that the man's confession:

It was determined that the confession made by Connelly should not have been suppressed (or withheld) and the Supreme Court overturned the state of Colorado's decision to suppress the evidence.  This was determined based on the case of Miranda vs. Arizona because there was not violation of the due process clause. 

The  ancient egyptians  who  built the pyramids  may have been  able  to move massive stone blocks across the desert by wetting the sand in front of a contraption  built  to pull the heavy objects