Plea on murder anniversary

Mr Blue was found outside his West End home

Detectives investigating the murder of a businessman attacked on his doorstep one year ago have interviewed more than 5,000 people.

Strathclyde Police admitted the inquiry into the killing of Alexander Blue had been "problematic" because witnesses were reluctant to come forward.

The 41-year-old died in hospital hours after suffering severe head injuries in the early hours of 25 June last year.

Mr Blue, who owned a taxi firm in Glasgow, was attacked at his home in the city's Dundonald Road, Dowanhill.

Detective Chief Inspector David Swindle, in charge of the inquiry, used the anniversary of Mr Blue's death to renew calls for people to come forward with information.

Effectively, the case will stay open until someone is brought to justice

DCI David Swindle

So far police have made only limited progress in tracing Mr Blue's movements in the hours before he died and establishing a motive for the killing.

He was seen leaving his taxi business at 1630 BST the day before he died and was later spotted at the Beanscene cafe in Cresswell Lane.

Police said they were still trying to establish whether he had been in the city centre that night and whether he was carrying a briefcase or meeting anyone at the cafe.

Detectives are also investigating a possible house purchase involving Mr Blue in the Westbourne Gardens area of Glasgow which may have been set up as a scam to dupe the businessman.

Mr Swindle said the inquiry was being hampered by the "mysterious nature" of Mr Blue and the shortage of information.

Mr Blue died in June of 2002

More than 5,000 people have been questioned on both sides of the border in connection with the inquiry, he added.

He said: "Someone out there knows something and, for whatever reason, they haven't come forward.

"Alex was a very private man and a very complex character. He was known by people from all walks of life which broadens possible motives for his murder - including financial and personal.

"We are trying to get the message across to people that they shouldn't assume what we know, but should come forward no matter what information they have about Alex's business or personal life.

"Although a year has passed, any new lines of inquiry will be vigorously pursued and there will always be someone actively working on the case.

"Effectively, the case will stay open until someone is brought to justice."

Cafe sighting

Police also issued descriptions of three men - one black and two white - who were seen with Mr Blue near the Beanscene cafe at about 2130 BST the evening before he died.

The man who is said to be black was described as being in his 30s, 6ft 4in tall, with a broad build, an English accent and black shaved hair.

One of the white men was also said to be in his 30s, had a body-builder type appearance, dyed blond hair and was 5ft 9in tall.

The third man was white, aged about 45, 5ft 8in tall, with grey, short unkempt hair. He was wearing glasses and a dark-coloured suit.