The chief executive at Matt Hancock’s local hospital is to step down before the publication of a delayed review into bullying allegations involving an unprecedented demand for fingerprints from senior clinicians first revealed by the Guardian.

In January 2020, a “rapid review” was ordered into claims of a “witch-hunt” at West Suffolk hospital trust, from which the former health secretary had to recuse himself because of his friendship with the trust’s chief executive, Stephen Dunn.

On Tuesday, Dunn announced he was resigning after what he acknowledged were “operational, structural and cultural challenges within the trust”. The trust’s deputy chief executive, Craig Black, will be taking over as interim chief executive while a replacement is found.

Dunn’s exit, after seven years in charge at the Bury St Edmunds-based trust, follows the departure of the trust’s medical director, Nick Jenkins, who stepped down to support his family. Its chief operating officer, Helen Beck, is due to retire in November.

The NHS has been criticised for taking its time to publish a review that had initially been promised in April 2020, but was delayed ostensibly because of the pandemic. In December, the Doctors’ Association UK said it suspected the conclusions were being sat on because they were likely to make embarrassing reading for Dunn, who was once described by Hancock as a “brilliant leader”.

Dunn was urged by the Royal College of Anaesthetists to end the “toxic management culture” after the Guardian revealed the trust had demanded fingerprint samples of senior clinicians in the hunt for a whistleblower who had tipped off a family about a potentially botched operation.

John Warby, whose wife, Susan, died after an operation in August 2018, was sent an anonymous letter highlighting errors in her procedure. A coroner concluded that errors in her care had contributed to her death. This led to a search for the whistleblower, which health unions described as a “witch-hunt”.

The incident, and other failings in patient safety, contributed to the hospital in January becoming the first to be relegated by Care Quality Commission (CQC) inspectors from “outstanding” to “requires improvement”.

Weeks before Warby’s operation, Patricia Mills, a consultant anaesthetist at the trust, had, along with a number of other colleagues, formally raised the alarm internally about patient safety over a doctor who had been seen injecting himself with drugs.

Dozens of staff had accessed Warby’s hospital records, but it was those who had expressed concern about the drug-taking doctor who were asked to provide fingerprint and handwriting samples, insiders claim.

As the same doctor was involved in Warby’s care, Mills, along with other colleagues who had complained, was immediately suspected by those investigating the leak of alerting her family to the errors.

Mills has consistently denied this. But managers demanded that she and other senior staff provide fingerprint and handwriting samples to prove it.

In an email seen by the Guardian, Beck had warned Mills that any failure to provide fingerprints “could be considered as evidence which implicates you as being involved in the writing of the letter”. Despite the email, Dunn claimed staff had not been threatened to provide fingerprints, and that the request was only voluntary.

In his resignation statement, Dunn said: “The last 18 months has presented operational, structural, and cultural challenges within the trust, with a challenging Care Quality Commission inspection locally and the overwhelming impact of the pandemic taking a toll on us all. I have been thinking about my position for some time but felt it was my duty to our amazing staff to lead the trust through one of the most difficult times it has ever faced.

“Now is the right time to step down, as we emerge from the brutal pandemic and refresh our strategy for the future.”

The trust’s chair, Sheila Childerhouse, said Dunn had led the trust with “passion and dedication”. She added: “We thank him for his commitment and leadership over the last seven years.”

Dr Jenny Vaughan of the Doctors’ Association said: “Our concern is that the report of the review into bullying allegations should have been published as soon as possible so that vital lessons could have been learned in a timely fashion. It has still not seen the light of day despite recent changes in the leadership of the hospital.

“Figures show that less than 60% of West Suffolk staff feel they are treated fairly when they raise patient safety concerns. We hope, despite this, that the report will be totally rigorous when it comes to examining the actions of the executive. An open safety culture is always better for patient care.”