Tricky one. I think if someone has shown genuine remorse and rehabilitation for their crime then yes, but each case would need to be judged on it's merits, and not a general rule that allows criminals out when they're old and sick. In Biggs case then yes. Despite his years on the run and cocking a snoot at the British legal system, he's now a frail old man with not long left in this world. What would be proved by keeping him inside? Alternatively i wouldn't agree that Charles Manson should ever be released, regardless of his health, based on his crimes and his lack of remorse for what he was responsible for. I would think that prison would appear to be more acceptable for some people if they knew they'd be allowed out to die in peace with their family towards the end.