Yes. Murder the person nearby.
No. Don't murder the person nearby.
Net gain of 4 lives.
Save the 4 lives.
Save one life, or save five? If that person would not be happy to die for the greater good, he or she is trash enough to die regardless.
What if the nearby person is your son or daughter. Then it becomes a emotional decision. Never-mind that, but I wouldn't place someone else in a position to die over the people that has. Because it would be best to allow yourself to be killed, if you wanted to play hero.
It is not your choice as to take or not to take a human life. The only thing you can do is attempt to save the people with the help of the bystander, and if you fail, then you fail, and you may have made a new friend along the way. The deaths of many do not justify the death of one, and our ancestors have died to ensure that such a maxim holds true. It is not okay during mass genocide to kill a person simply because everyone else is being killed any way, even if such an act would be the last and therefore end the genocide.