Except murder, and offences against the State punishable with death, nothing is an offence which is done by a person who is compelled to do it by threats, which, at the time of doing it, reasonably cause the apprehension that instant death to that person will otherwise be the consequence:
Provided that the person doing the act did not of his own accord, or from a reasonable apprehension of harm to himself short of instant death, place himself in the situation by which he became subject to such constraint.