If someone is killed and is dead for 5 minutes and comes back to life is it still murder?

That is not really possible to come back to life after flatlining- if the person does not respond immediately to a high dose of adrenaline and is flatlining for 5 min he will be dead and it would be murder. If he doesn't die in the first place (heart never stops) then it won't be murder. You are watching too much tv. :-)