Judge Martin Beddoe said Osofsky and other senior SFO officials should not have had contact with the investigator, who had no recognized legal role in the case.
In a ruling, he criticized Osofsky for tacitly encouraging Tinsley, who had pressed the suspects to admit their involvement in a global system of corruption.
The SFO is setting up an investigation after the judge said that his contacts with Tinsley should be “thoroughly examined to see what lessons can be learned from them”.
Sue Hawley of the Spotlight on Corruption anti-corruption campaign said: “It was a serious error in judgment. . [Osofsky] went over the heads of his staff and behind the backs of lawyers defending those whom his agency was trying to prosecute, to hire an unofficial independent operator. ”
Osofsky, a dual American / British national, was appointed director of the SFO two years ago after working for the FBI and commercial companies.
His behavior was revealed during a corruption trial when an accused tried to dismiss the prosecution against him.
The restrictions on disclosure – which ultimately failed – were lifted after the trial at the Southwark Crown Court in London.
Two businessmen were found guilty of conspiracy to make corrupt payments to win huge contracts in the Iraqi oil industry.
They were prosecuted by the SFO, which spent five years investigating allegations that Unaoil, a Monaco-based consultancy, paid bribes worldwide to help secure contracts for multinationals that had hired the company.
One of them was Ziad Akle, 45, responsible for the territory of Unaoil for Iraq. In January, at the start of the trial, Akle’s QC, Jim Sturman, said that the prosecution should be stayed because he could not receive a fair trial.
He argued that Tinsley and the SFO had “brazenly flouted” guidelines designed to ensure that improper pressure was not placed on an accused to plead guilty.
Sturman described the “large number of contacts” between Osofsky and other senior SFO officials and Tinsley, whose firm, 5 Stones Intelligence, takes its name from the Bible.
In an exchange, Tinsley texted Osofsky with the message “mercy means valuing relationships over rules”. “Inspirational,” she replied.
In another exchange, Tinsley told Osofsky after a successful meeting, “We are moving towards a good solution … you are the bomb.” She said that a colleague had “joined the DT fan club”.
Osofsky told Tinsley that she was “very honored” that Tinsley “is going to us” and “we are working well together and will continue to do so”.
Sturman accuses him of texting Tinsley as a teenager who had just found a new best friend.
Tinsley had been hired by members of the Ahsani family, the owners of Unaoil, after the SFO and US prosecutors opened an investigation.
Sturman told the court that while working for the Ahsani, Tinsley approached Akle and another suspect behind the backs of their lawyers and improperly “intimidated” them to plead guilty to corruption charges.
Tinsley made false promises that they would be treated leniently in return, according to Sturman. He told the court that Tinsley then communicated the details of his discussions with Akle and the second suspect to Osofsky and others at the SFO.
Beddoe denied the request but said he “had maintained some of the criticism that has been advanced at a very high level within the SFO”.
He said that Osofsky and other members of the SFO would have nothing to do with Tinsley, who he said was “someone who had no official status, who was not employed by any American government agency, was not the lawyer of the Ahsanis (not a lawyer at all), but an independent agent who obviously acted only in the interest of the Ahsanis… and they should not have tolerated and even less encouraged (if only tacitly) his contact “with Akle.
According to Beddoe, Tinsley “did not hesitate to flatter Ms. Osofsky and talk about her talents, and unfortunately Ms. Osofsky made herself vulnerable to them.”
A spokesperson for the SFO said: “The judge in this case found no evidence that the SFO acted in bad faith, nothing illegal and nothing to prevent the case from being tried.
“We accept his criticism of the way a contact was treated. A review will be carried out on this subject and a protocol covering contacts with non-legal representatives has been put in place. ”
Beddoe ruled that the SFO’s relationship with Tinsley had not affected Akle during the investigation and that Tinsley had not broken any rules.
The Ahsani were not tried in the Southwark case. Last year, Cyrus Ahsani and his brother Saman pleaded guilty in US court to conspiracy to facilitate bribes on behalf of multinational companies to obtain oil and gas contracts.
Stephen Whiteley, an Anaoil manager, was also convicted.