THE lead inspector investigating Police Scotland's anti-corruption unit is a former detective who worked with the four officers at the centre of the row into snooping on journalists’ sources.

Stephen Whitelock, tasked by a watchdog to review the Counter Corruption Unit, was the “head of intelligence” at Strathclyde Police.

Labour MSP Graeme Pearson, himself a former top police officer, said the appointment gave the impression of a “conflict of interest”.

Police Scotland last year breached tough new rules requiring forces to seek judicial approval before using snooping powers to flush out a journalist’s sources.

The five “reckless” breaches related to a newspaper story into Strathclyde Police’s flawed investigation into the murder of prostitute Emma Caldwell.

Without judicial approval, the single force used the Regulation of Investigatory Powers Act (RIPA) to find out if serving and retired officers had passed information to a media outlet.

The unlawful activity sparked probes by the Holyrood Justice Committee and Her Majesty’s Inspectorate of Constabulary in Scotland (HMICS).

The Herald:

Picture: How the Sunday Herald broke the spy story

The Herald:

Picture: The Emma Caldwell link

MSPs have heard from deputy chief constable Neil Richardson and assistant chief constable Ruaraidh Nicolson, but their investigation has been marred by a row with the force.

The Committee also wanted to hear from four officers involved in the controversy: Detective Superintendent David Donaldson; Detective Inspector Joanne Grant; Detective Superintendent Brenda Smith; and Chief Superintendent Clark Cuzen.

At last week’s Holyrood hearing, Nicolson said that a senior officer – in this case Smith – had flagged up concerns internally around RIPA applications relating to journalism: “In more general terms, she expressed concern round about the applications for journalistic material.”

However, Police Scotland failed to pass on the Committee’s invitations to the four officers.

Cuzen, Donaldson and Smith, through their staff association, then declined the opportunity of appearing in front of MSPs.

Niven Rennie, the president of the Association of Scottish Police Superintendents, informed MSPs that the officers intended to “fully assist” the HMICS, adding that they believed this probe would provide “further clarity”.

However, the independence of the HMICS review into the CCU may now be under threat.

Stephen Whitelock, described as HMICS’s “lead inspector” in the case, held various senior positions at Strathclyde and at the Scottish Crime and Drug Enforcement Agency during a 34 year career.

He was Head of Intelligence and Joint Head of CID at Strathclyde before becoming the SCDEA’s deputy director general.

The HMICS has confirmed that he worked with the four named officers during his police career "at one time or another".

In September, the Sunday Herald revealed how half of the lead inspectors in HMICS, whose job is to provide “independent scrutiny” of the single force, are former police officers.

The Inspectorate review will include an examination of the “circumstances” which gave rise to the RIPA application breaches.

It will also involve interviews with “relevant senior officers” and focus groups with CCU staff.

More importantly, some of the former and serving officers targeted by Police Scotland are believed to taking their case to the Investigatory Powers Tribunal, which can award compensation.

Scottish Labour justice spokesman Graeme Pearson, former Director General of the Scottish Crime and Drug Enforcement Agency, said: “I have no reason to doubt Stephen Whitelock’s integrity. The knowledge and skills required to conduct a review properly are held by very few police officers.

“However, it’s unfortunate that his appointment gives the impression of some conflict of interest and I would like to think the eventual report will display that impression had no impact.”

He added: “It would have been better had there been someone completely unconnected with the circumstances.

“But I have no doubt, knowing his background, that he will take all necessary evidence and report properly on what he finds.”

A spokesperson for HMICS said: “Stephen Whitelock joined HMICS three years ago after a 34 year career in policing. During his policing career he did work with all the named individuals at one time or another, however he does not have any social or personal associations with any of them.

“It is also relevant to highlight that he has had no involvement with CCU and no personal involvement with the circumstances surrounding the [Interception of Communications Commissioner's Office] report nor the original murder enquiry. When Joint Head of Strathclyde CID, he had portfolio responsibility for Intelligence with major crime investigations being in the portfolio of his counterpart.”