They saw no point in dying in prison and decided that they had to escape which was a decision that led directly to the butchery of Police Officer Hawkins.
We must never forget that life sentences on people who cannot ever be released incentivise them to the worst of possible actions.
Hmm. I wonder what the only legitimate alternative might be?
In this country the number of people killed by released 'lifers' is a statistic carefully guarded by the government.