A garden hose would be appropriate when two more or less euually-matched drunk guys were rolling, boxing, or otherwise dueling/play-fighting on your lawn. A garden hose is not the appropriate response if you believe one person is attempting to kill another. The idea of the garden hose is to shock someone and "wake them up" so they take a moment and get a chance to think about what they're doing. It's not used to stop someone who knows what he's doing, has done it before and is doing his best to kill someone this time.
Now, let's get a quick reality check on "head locks" and "chokeholds."
Some of you, when hearing "headlock," are picturing a folkstyle wrestling headlock. As someone pointed out earlier, this would be with the victim's head against your ribs, your arm over the head against the neck and nestled under the jawline, your other arm encircling under their opposite arm and hands clasped.
This, as pointed out, is the only legal hold in folkstyle wrestling because it is not a choke hold or a serious neck crank. It's used to control and direct the victim's body. However, if you're a LOT stronger than your victim, you could probably crank the neck pretty hard even from here.
However, a "headlock," if the victim is facing her tormentor, could also be what submission wrestlers call a "guillotine." In applying a guillotine, the idea is to have the opponent's head against your ribs, one arm looped around the neck, and the hands clasped. You want the wrist of the choking arm turned so that the wrist bones cut into the neck. Both their arms need to be outside the hold for this to work.
The standard teaching in BJJ is that once you get the guillotine sunk, you need to fall back to "guard" position--your legs around his hips, controlling his body. Then you arch your back and the pressure all goes to his carotids and his airway. Because you control his hips with your legs, he can't roll back and make room very well, which would counter the choke.
Again, though, if you're a lot stronger or your opponent doesn't know the counter, that's not necessary. You can power through it and he'll sleep. Keep cranking after he sleeps, and he dies. It's not as easy to "snap" someone's neck as a lot of people think (Steven Seagal movies to the contrary) but if you have control of his body structure I'm sure it can be done--and again, that goes double if you're much bigger and stronger. I'm about 330 and I can power through a guillotine on most of my classmates, but I'm not allowed to do so because it probably wouldn't work on someone my size.
Now, for how long it takes to reach unconsciousness:
It's easy to go out by accident even when you're sparring with someone who expects you to tap and will stop when you do. You can get light-headed in a couple of seconds. I've felt the tunnel closing a couple of times already, and last night one of my training partners actually had everything go black and the sound cut out on him. We were face to face so I had a good view of his face and released it at that point.
The instructor told us last night that ten seconds is the rule of thumb once you think you've got it sunk in--if you're in and choking and he's lasted ten seconds "and he no tap and he no sleep, something wrong. Do something else."
Anyway, I'm his size and now have a small amount of grappling training. I'd be hard pressed to choose between trying to take his back and sink my own rear naked choke, for example, or drawing a pistol if I had one. Standing rear naked works, but only if you can sink it, and you have to think about his wife, too. Of course shooting right next to her is probably not any safer. If you yourself are too injured or too hampered by your brace, the decision gets easier. But the shooter knew this wife-beater better than I do, which could be good or bad. Might turn out that he knew enough to know he had to go straight to lethal force. Might turn out that he knew more about the officer's domestic life than the press does and this led him to decide it would be better if the officer died instead of just stopping.
His superiors can say what they want, but I doubt they're sleeping well at night. If they'd taken this guy seriously, this might not have had to happen. Their attitude that it wasn't a big deal and he should slide by with some counseling was almost guaranteed to lead to someone's death. I'd have bet on it being the wife's.
It's too bad the wife didn't leave him before it came to this, but such is life.
