The Crown Prosecution Service has dropped its investigation into an MI5 officer accused of complicity in the mistreatment of Binyam Mohamed.
The officer, known as Witness B, interviewed Mr Mohamed when he was being held in Pakistan.
Director of Public Prosecutions Keir Starmer QC said there was insufficient evidence to prosecute the officer.
MI5 chief Jonathan Evans said he was “delighted” by the DPP’s decision not to prosecute the “dedicated” officer.
On Tuesday the government confirmed it had paid compensation to 16 Guantanamo Bay detainees – including Mr Mahomed – in an out-of-court deal.
That deal, which is confidential, is thought to run to millions of pounds and includes a payment to a man still held in the US detention facility in Cuba.
The settlement of the claims, and today’s decision by the Crown Prosecution Service, leaves one outstanding investigation into an MI6 officer, which the secret intelligence service referred to the police.
In his statement, Mr Starmer said: “The Crown Prosecution Service has advised the Metropolitan Police Service that there is insufficient evidence to prosecute Witness B for any criminal offence arising from the interview of Binyam Mohamed in Pakistan on 17 May 2002.
“We are unable to release further information at this stage because the wider investigation into other potential criminal conduct arising from allegations made by Mr Mohamed in interviews with the police is still ongoing.”
Witness B was at the heart of allegations made by Mr Mohamed that the British security and intelligence agencies knew that he had been mistreated and tortured.
Mr Mohamed was arrested in Karachi in April 2002 and taken to a detention facility. There, CIA officers questioned him about alleged links to terrorism.
But he was then subjected to what the Court of Appeal in the UK later described as “at the very least cruel, inhuman and degrading treatment”.
This included threats, sleep deprivation and shackling, part of a CIA-approved plan to use harder interrogation techniques against key suspects.
On 17 May, an MI5 officer using the name John conducted a three-hour interview with Mr Mohamed at the detention facility.
Mr Mohamed says that during this interview, which was also attended by a US agent, he was told that he could be removed from the facility and taken somewhere else to be tortured by “the Arabs”.
But in his evidence in the High Court, Witness B denied the claims made by Mr Mohamed, saying that he told him he could use his influence to help the detainee if he was persuaded that he was being truthful.
The Intelligence and Security Committee later reported that the officer was “experienced” and had conducted the interview in line with MI5’s then guidance on contact with detainees held by foreign powers.
The CIA later flew Mr Mahomed to Morocco where, according to court papers, he was subsequently subjected to torture including cuts to his genitals.
In a statement, MI5’s director general Jonathan Evans said: “I am delighted that after a thorough police investigation the Crown Prosecution Service has concluded that Witness B has no case to answer in respect of his interviewing of Mr Binyam Mohammed.
“Witness B is a dedicated public servant who has worked with skill and courage over many years to keep the people of this country safe from terrorism and I regret that he has had to endure this long and difficult process.”
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