ONE of Britain's leading criminologists says today that there should be two separate but linked investigations into the murder of Nairn banker Alistair Wilson.

Mr Wilson, 30, was shot on the doorstep of his family home on November 28, 2004, and died later that night in hospital. No one has ever been arrested for the murder.

Police have suggested that the killer is believed to have been in his 30s.

In an exclusive article in today's Herald magazine Professor David Wilson, emeritus professor at Birmingham City University, says: "With every cold case I always argue that they are solved by 'shaking the tree'.

"When a crime first occurs that 'tree' of suspects, witnesses, alliances, people of interest ... is strong and resolute and not too much intelligence can be gathered.

"However, over time, old friendships falter and people move on; local networks that had once been firm and unwavering begin to break down. Shake the tree years after the event and leaves and branches begin to fall to the ground in greater numbers and this becomes intelligence which can be harvested to help to solve the case."

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On the subject of the two investigations he says he would firstly enquire into a person who was seen knocking on Mr Wilson’s door on the night he was murdered, "and issuing any efit that had been produced to the public.

"Second, and this is more difficult, I would be looking very carefully at Mr Wilson’s business clients at the bank. Who did he have particular dealings with and who stood to lose by him leaving his job? What was it that they feared that he might discuss after he had left the bank?

"Frankly, I have never seen a statement from HBOS about Mr Wilson’s work, or his list of clients ...for it seems to me that the contractor of the hit will emerge from this aspect of Mr Wilson’s life.

"In short, this hit increasingly bears the hallmarks of white-collar crime, as opposed to the blue collar crimes of drug dealers, robbers and street hustlers."

Full story in today's Herald Magazine