“In 2009 my constituent Mr Samuel was acquitted of common assault after an unsuccessful prosecution centred on a fabricated witness statement by the police,” the former Tory leader told parliament on Tuesday. “Since then, his efforts to seek redress through the courts have been frustrated by a cover-up that reaches right to the top of the Crown Prosecution Service.”

Nazir Afzal, a former chief crown prosecutor, said the alleged behaviour of the police “stinks” and some of the decision-making by prosecutors “beggars belief”.

Samuel is suing the Metropolitan police and the CPS for misfeasance in public office, conspiracy and malicious prosecution. His claims have been struck out, but he is preparing to appeal.

The news is potentially serious for Saunders, who was criticised last week for saying some rape victims who stayed silent during an attack could give the impression they were consenting.

In 2008 Samuel complained to police officers about their treatment of Jo, who suffers from sickle cell anaemia. Officers and ambulance staff had been called to the family home to deal with Jo’s “vaso-occlusive crisis”, which can cause organ damage.

Samuel became infuriated when detectives arrested his pregnant wife on suspicion of attacking him. He claims the police action prevented her from obtaining immediate medical treatment.

Two months later his wife was cleared — but Samuel found himself charged with common assault after the same Met police officer claimed Jo had made a statement alleging her husband had beaten her. Samuel and his wife deny she made such a statement, deny having seen a statement and are amazed the police claim they took it from her when she was on strong painkillers.

Internal police logs seen by The Sunday Times also reveal that on the day Jo was said to have given the statement, the police officer in attendance said she was “distressed” and that “information was very difficult to extract from her”. The day after the police say Jo gave the statement, the log records an officer in the case saying investigators needed to “obtain” a statement.

“It was forged. I never made a statement,” Jo said. “This case is really murky. They tried to frame Ade. Most people wouldn’t believe what went on.” The CPS charged Samuel despite Jo’s repeated complaint that she had been “misrepresented” by police, internal CPS files show.

He says he was not served with the witness statement before his trial at Waltham Forest magistrates’ court, at which he was acquitted. Afzal said omissions by junior prosecutors were “completely bizarre and require a full explanation”.

After his acquittal, Samuel launched a series of complaints to Scotland Yard and the CPS backed by Stella Creasy, his then constituency MP. Saunders, who was the chief crown prosecutor in London at the time, replied to Creasy in August 2010 on behalf of the CPS.

Saunders backed the prosecution and described Jo’s statement as “clear and detailed”, despite, it seems, not having seen it herself. The DPP also said there was “no suggestion of the allegations having been fabricated by her [Jo]”. However, Jo had told the CPS that the “only true statement” she made retracted all allegations against her husband, who she described as “not guilty”.

Saunders told Creasy that inquiries had been hampered because the statements were “missing”. However, her letter did not say that, by this stage, the CPS had a note on file that the officer in charge of the original investigation had taken them from Scotland Yard’s archive. They have never been found.

A statement from Saunders said there was no reason to believe there were “any material inaccuracies” in the briefing used to prepare the letter. She and the CPS “absolutely refute any suggestion that any actions were carried out in bad faith”. They deny there had been any conspiracy, falsification or cover-up and and say there was no credible reason for such claims. The Met said Samuel’s complaints were not upheld and it could not comment further because of the litigation.

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