A gun close by
My father killed himself with a perfectly legal gun left over from his law enforcement days. He kept it long after he retired in the top drawer of a mahogany chest of drawers in our big hall, unloaded but right beside the ammunition. My brother and I knew not to touch it, not ever.
Dad was troubled about his health, and the gun was handy and available that December morning.
I don’t know whether he would have used another method. I just know he didn’t.