The Mail Online report:
More than 1,300 suspected criminals including alleged rapists, child molesters, violent offenders and at least one murderer have escaped justice in the past five years because of police blunders over arrests.
Figures show that errors in paperwork, failure to read suspects their rights or mistakes in the way officers conducted interviews have meant at least 200 suspects a year walked free without charge.
Since 2008, these have included 262 suspected violent criminals and 21 sex offenders, three of whom were suspected rapists and one of who was accused of sexually abusing a young boy.