Meep, I don't know any men who got into scrapes, fights whatever, excpet for one friend who was attacked by some drunken idiots. I seem to be related to, and attracted to, as friends or partners, men who feel no need to be dickswinging thugs who cannot control themselves or their drinking, or who feel entitled to hurt others. Y'know, normal men. Like normal women don't do that shit. Normal people.
As others have said, OP, attempted murder does not mean 'really hurting someone in the heat of the moment, not realising how far you were going' - that would have meant he'd have been charged with something else. Attempted murder means a conscious, deliberate choice to try to take the life of another human being. Believing you have the right to kill.
If he really hasn't thought about him wanting and trying to kill someone, for over ten years, he is either lying, or a stunningly cold psychopath. If you had almost killed someone, wouldn't you be wracked with guilt over it, daily?!
Then add to this his lying to you over it. Being in prison for making a decision to kill another person is something pretty big. Someone who is genuinely a decent, moral person, with even the slightest insight into their behaviour and crime, would want to let potential/new partners know, so they can make their minds up about continuing a relationship with them.
He is really not looking like catch of the year. I would run for the hills, personally. The family must be awful too, colluding in keeping this secret and sweeping it under the carpet.