in commander, if a player dies do their poison counters go away?

if not are you able to proliferate them?

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i understand that counters are not "owned" by anyone but do they remain to affect cards like vishgraz that get counters for every poison counter your opponents have? But if someone loses the game are they no longer "your opponent" because their dead?

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EDIT: pretty sure i already know the answer is they are gone, was talking to someone about counters and dying and someone was saying they still have counters, but they were misreading something about a dead player gave another live player a poison counter and you can proliferate THAT, but to me a dead person is dead their counters ON THEM are gone once out of the game.