When a police officer writes out a witness statement for a potential prosecution witness, it always ends up being made, in a detrimental way against the person, or persons suspected - if such a witness says anything which might tend to put a suspect in the clear, such a statement will not form part of the prosecutions case! Police officers manipulate evidence, they record information in such a way, that is at odds with the actual truth, they portray the facts as though they support the commissioning of some offence, or other..
But..