OK, i was wondering about the area with the green hot boiling lakes. I came across 3 guards and a prisoner. I had the option to set him free.

I did set him free, then i kill the 3 guards, (imperial guards). The game then auto saved.

Does that mean the imperial guards now want me dead? bounty? will they attack me on sight?

Yes you will have a bounty as a murderer.

What can i expect? Will people come after me? or will i just have trouble when i stumble across more imperial guards.

Not even sure why i did it. The guy i set free did not even stick around to thank me. Wait till i get my hands on him.

LOL I did the same thing oh how I love going from a good guy to a bad mother [censored] in less then a second.

If he killed all the witnesses, he shouldn't have any bounty.

Key word.

He probably still will because that system is broken beyond all possible belief.

Yep, if you kill all of them, nobody will attack you for that. no witnesses, no crime.

Trust me, am in the black brotherhood

But a question remained anyway, what does it change in the game? Because we dont won anything when we save them.

Why do you even ask? Just go experiment yourself.

I do, i have save a lot and they die 5 meter after against a wolf

I have done that a few times without ever getting a bounty.

I killed a Thalmor patrol tonight (what a bunch of butt-nozzles those guys are) and set their prisoner free. Then I continued on my way to the next major town, which was quite far... yet when I arrived, three guards immediately began pelting me with arrows and a tavern drinker ran out to punch my face. My bounty was listed as a measly 40 gold, and I was unable to yield to any of my attackers.

Fortunately, I'd saved right before my attack, so I tried it again, only this time I humanely dispatched the prisoner, too. "He was compromised," my character muttered to himself. Voila, no bounty. It seems the game's system isn't smart enough to recognize a 'witness' that's on your side and has a vested interest in shutting up. Either that or the guy was a double agent.

Still seems broken to me in that i don't think a rain of arrows is an appropriate response to a 40-gold bounty.

Actually I did the same thing. I came across two imperials and a stormcloak prisoner and killed the guards, he escaped and later I went to a imperial camp and nothing happened.

I did the exact same thing, i set him free and gave him an imperial sword to help me fight them although he decided his Nord fists were a better option.

Anyway, i killed all 3 guards and sadly the Nord also died. I had NO bounty when i killed the last guard.

i did the same thing and gave the prisoner a sword he didnt use which i lost... after i killed the guards i didnt get any bounty.. i guess it depends on where u encounter them and how close to civilisation u are to get bounty.

Fix'd

It's not classed as murder if they attack you first. I've killed and looted quite a few this way.

always talk to the leader guard first to ask why the prisoner is beeing a 'prisoner', it will often give u the idea whether its a good or a bad thing to set them free.

example:

I am turning into one bad mother fecker. Tonight i will kill everybody in the city of Winterhold.

and thats related to this topic because... ?