The law firm conducting an independent examination into the links between Craig Whyte, Charles Green and Imran Ahmad, and the latter pair's management of Rangers, has engaged a Queen's Counsel to oversee the process.

Pinsent Masons moved to appoint Roy Martin QC, a former Dean of the Faculty of Advocates.

Martin, one of Scotland's most eminent legal figures, will assess the information collated by the investigation, which also involves the forensic arm of accountancy firm Deloitte.

Since the inquiries began last week, computer files, phone records and paperwork have been collected, while offices were searched. A verbal report was due to be made to the four non-executive directors – Ian Hart, Walter Smith, Bryan Smart and Philip Cartmell – at the beginning of this week.

Whyte claims that he and his business associate, Aiden Earley, were directors and funders of Sevco 5088, the company that signed an exclusivity agreement with the administrators Duff & Phelps last summer. However, when Rangers Football Club plc went into liquidation, the business and assets were sold to Sevco Scotland.

Green and Ahmad have always insisted that they were stringing Whyte along to buy his shares should RFCplc have gained a Company Voluntary Arrangement to emerge from administration, although Whyte contends otherwise. Green and Ahmad have both now left Rangers, although the investigation will continue to look at their management of the business since last May.