Nope. There are tons of thought experiments that explore possible differences between killing and letting die. Every single one of them leads me to the same conclusion.

It kind of depends on the situation, don't you think? Like if it's a frat house and someone is passed out cold from drinking & drugs but no one calls an ambulance, then I would say they could be considered complicit and they should be held responsible. If you're just a bystander and something happens suddenly, you may be too shocked to act quickly, or if it's a dangerous situation, you shouldn't be held responsible.

No..

According to Peter singer yes since the result is the same.

However I don't see Peter singer heading over to Africa to feed starving kids so he obviously doesn't really believe what he says.

Honestly no because to say otherwise just means that someone can keep making it harder to help an prove that you can't make a line that is logical.

What is a bystander? 50ft, 100ft, 2000ft? At what point do I have to give up everything I own and all my time because someone somewhere is in pain?

You state that the person can swim, so he has a choice there, but the first port of call is.....call the professionals. Son is a firefighter and on their talks to the community they always say do not risk your own life, you may endanger ours when we get there. They would prefer practical help - clear the site, give clear descriptions to the responders, support the victims, yes give CPR if needed. He has twice had to rescue unfortunate Samaritans. One had a car roll on him trying to get someone out where the fire service would have stabilized the vehicle first and then executed the rescue.
There is empathy and then common sense, we cannot save the world.

She is no cunt. what that even mean? I will tell you what it means. It indicates you should spend a bit of time developing your ability to communicate and not use these outdated moronic statements. I know you posses the ability for eloquence. Use it.

This situation is sticky. If you have to risk your own life to help then probably not. In other situations, yes they should be held partially responsible. They obviously shouldn't be charged with murder or manslaughter etc., but the penalty should be severe enough to make others act in benefit of the person that needs help. It doesn't take much to call 911 and give them your location. That should be the required minimum.