If the gun and the car both belonged to him and the suicide note was in his handwriting in his home then it was definately murder ,because all it would take is for armed government agents or enron hit men to sneek into his well protected (I am sure) home... force him to write a credible note,find a gun he has around the place , force him to hop into the car (all this without his wife,child or servants seeing it)drive undetected to the correct place and simply force him to pull the trigger.These murders are daily occurances as we all know.
This is scarcasm for those who cant recognize it