Scotland’s police chief has said the force has a “resolute determination” to solve the murder of a banker who was shot on his doorstep exactly 20 years ago.

Father-of-two Alistair Wilson, 30, was murdered on November 28, 2004 at his home on Crescent Road, Nairn, in the Highlands.

Detectives have examined thousands of statements and documents but his killer has not been found.

In September, Lord Advocate Dorothy Bain KC announced the case would be reinvestigated under Operation Sabine, with a new team of officers and prosecutors.

Speaking at a Scottish Police Authority Board meeting on Thursday, Police Scotland Chief Constable Jo Farrell said she wanted to acknowledge the 20th anniversary of Mr Wilson’s murder.

She said: “Today Police Scotland makes a fresh appeal for information relating to Alistair’s murder.

“We would repeat our appeal that anyone with information please contact us on 101 or through our dedicated online portal, which can be found on our website.

“A new investigation team is in place and detectives will examine evidence gathered over the last 20 years, as well as investigate new opportunities for fresh lines of inquiry such as advantages in technology and forensic testing.

“We are committed to this reinvestigation and I would underline our support of Alistair’s family and our resolute determination to bring those involved in Alistair’s murder to justice.”

After the reinvestigation was launched, Mr Wilson’s family said they had lost confidence in the senior leadership of the police to solve the murder and criticised Ms Farrell, telling the media she did not have immediate plans to meet with them.

A team of 14 officers are now working on Operation Sabine – drawn from specialisms including complex investigations, homicide and murder inquiries, forensics and intelligence gathering – with more being drafted on to the inquiry in the coming weeks.

They will look at around 10,000 documents, including roughly 6,000 statements, and also examine 14,000 actions carried out by police since the murder.

The force has now launched a major investigation public portal that allows people to submit files and information to the team anonymously to help solve the murder.

Alistair’s wife Veronica, their two sons and wider family have suffered 20 years of pain and their unanswered questions about why he was murdered and who was responsible remain

Mr Wilson was shot at about 7pm on Sunday November 28 after a man called at the family’s home and spoke to his wife, Veronica, who had answered the door, and asked for her husband by name. He then went downstairs to speak to the caller.

Mr Wilson was handed a blue envelope with the word “Paul” on it, went inside briefly and then returned to the door for a second time, where he was fatally shot.

He died later that evening in hospital.

The gun, a Haenel Suhl pocket pistol from the 1930s, was recovered from a drain near his home 10 days after his murder.

Detective Chief Superintendent Suzanne Chow said: “The team reinvestigating Alistair’s murder are absolutely committed to doing everything they can to get justice for his family.

“We are exploring all new opportunities available to us, including advanced technology around forensics and DNA analysis.

“Alistair’s wife Veronica, their two sons and wider family have suffered 20 years of pain and their unanswered questions about why he was murdered and who was responsible remain.

“The thoughts of everyone at Police Scotland are very much with them at this time and we are keeping them informed of any updates we have as the reinvestigation progresses.

“I am determined that the passage of time is no barrier to justice and we are absolutely committed to finding out who was responsible and bringing them to justice.

“The new major investigation public portal is another option for the public to send us information directly and anonymously if they wish.

“A significant anniversary such as this will prompt further discussion both in the local community and across the country around this investigation, and I would urge anyone with information – no matter how small or insignificant they think it might be – to speak to us and help get justice for Alistair’s family.”

The Operation Sabine public portal can be accessed at https://mipp.police.uk/operation/96HO020108N02-PO1.