Richard Halfpenny's attitude (Opinion, April 10) is depressingly predictable.

James Hanratty may well be guilty after all but that does not mean they get it right in all cases.

Timothy Evans was innocent. That did not stop him being hanged for a crime committed by John Christie.

Richard Halfpenny tends to forget that, in the Stefan Kiszko case, forensic evidence that proved it was impossible for him to have committed the crime was deliberately withheld from the defence.

As a former police officer, having served in both Sussex and West Yorkshire, I can tell Mr Halfpenny and his supporters that perjury within the police force is endemic.

I have lost track of the number of times I was asked to commit perjury in order to make my evidence more concrete.

I worked for a Superintendent who openly admitted he would deliberately cross-contaminate his forensic evidence. Before anyone asks the obvious question, yes, I did give evidence against him.

It is because of my constant speaking out that I was fitted up for a crime I did not commit. It took nine years to clear my name in an uncontested appeal.

From personal and bitter experience, I can tell Mr Halfpenny that our legal system is shot through with corruption. Until there is a determined effort to root that corruption out, no conviction is safe.

-Stuart Bower, Hawkhurst Road, Brighton