Lancashire Police civilian worker Susan Lyons, based at Bamber Bridge, could have been jailed for 12 months if convicted of sending indecent material to two North Yorkshire Police officers.

But early in a trial at Teesside Crown Court, Recorder of Middlesbrough, Peter Fox QC, intervened and called an end to the prosecution, criticising police.

Miss Lyons, 44, of Ingol, Preston, and ex-partner John Bell – now serving four years for her attempted murder – were arrested last June and questioned about images found on a computer.

After being released on bail, the couple fled to Scotland and, in an alleged suicide pact, took the indecent pictures of one another and sent them, along with a scribbled note, to the officers.

Within an hour of sending the package, Miss Lyons' partner had tried to kill her.

Bell, from Richmond, North Yorkshire, left her with life-threatening injuries after they drove to a forest and he hacked at her with a large fishing knife.

The judge said the police and prosecutors should have reconsidered their stance after learning that Miss Lyons was in fear of her life from her lover when she posted the envelope.

He condemned the handling of the case by the North Yorkshire force and the Crown Prosecution Service and accused them of "systemic failure."

He said the officers in the original case, DC Paula Adair and DS Dave Peart, should not have questioned Miss Lyons because they were effectively the complainants in the pictures case.

Judge Fox said he believed DC Adair was "insulted and humiliated" by the photographs.

He added that the case should have been handed over to colleagues, and accused the detectives of carrying out a private prosecution using the whole might of the police force.

A formal not guilty verdict was recorded against Miss Lyons.