But can anyone possibly know that you knew? Sure, you can suspect. You can even strongly believe. But until I actually blow my brains out, you can't possibly know.
But I was thinking more along the lines of Kevorkian, with his suicide machines. (Incidentally, I believe in assisted suicide: if someone wants to off themselves, who are we to say they shouldn't?) Technically, these machines serve only one purpose: to allow the user to commit suicide, presumably painlessly. But providing the equipment isn't the same as injecting the drugs, or pulling the plug, or whatever else you might do. Sure, there's a 99.9% probability that the person is going to kill himself, but there's also a 0.1% possibility that he won't.
But if I supply you with the means, and then goad you into actually using them, that's another story altogether. Isn't it?