Should the President be guarded by unstable men ?

http://www.inquisitr.com/385359/obama-bodyguard-found-dead-in-apparent-suicide/#4C5E8UrbEblh6ihH.99

The cause of death was determined to be carbon monoxide poisoning. Prieto was found unconscious in his car with the engine running. His death is being investigated by the DC Metropolitan Police and the medical examiner’s office.

No, the president shouldn't be guarded by unstable men. But I would guess that psychiatric evaluations are standard for Secret Service positions?

he prolly saw something he shouldn't have