Well I don't know if there would be any chest pain, but have you ever laid down for a while then stood up suddenly, I would imagine this would be the feeling it would cause, because in all causes of the death the cause of death is the brain not receiving oxygen,whether it be by decapitation, organ failure, drowning, choking, etc. Any pain would be a result of any condition leading up to death however death itself is pretty painless. And the same happens when you stand up too fast only you regain consciousness immediately instead of dieing.
Nobody can tell because victim becomes dead. Its symptoms are no pulse, no breathing, sudden collapse, unconsciousness etc. For details, visit this link.