He was dressed in dark clothing, probably a grey shirt, and he probably got away with murder.

After thousands of hours of interviews, inquiries, searches and other detective work, police have been unable to identify the killer of gentleman grocer Frank Newbery with a coroner making one final plea for information yesterday.

Deputy State Coroner Mark Buscombe found that Mr Newbery, 87, who was found unconscious in his Newcastle shop on March 12, 2007, was attacked by a person or persons unknown.

A police statement tendered to Newcastle Coroners Court stated that police believe it was a robbery gone terribly wrong despite $1500 cash being found in one of Mr Newbery’s pockets.

Two witnesses saw a man in Frank’s Ham and Beef after 4pm on March 12 and despite subtle differences in their descriptions, police believe this man was probably the killer.

However, despite an exhaustive investigation and a number of suspects being identified, the identity of the killer remains a mystery.

Mr Newbery founded the business in Union Street 58 years before his death and was known to provide outstanding service to elderly and frail customers.

He was on his own in the shop for the first hour of trade each day and the last hour between 4pm and 5pm, a police statement said.

Among the lines of inquiry was an anonymous tip-off to Crime Stoppers several weeks after the murder, an anonymous letter sent to Mr Buscombe accusing two unnamed prostitutes and extensive inquiries into a man with schizophrenia who committed a number of violent robberies in 2007. All proved fruitless.

Detectives analysed hundreds of other robberies, former prisoners on parole and took DNA swabs from just about every person who entered the shop on the day of the murder, including police and ambulance officers, in a bid to match DNA samples taken from the scene.

Two DNA samples remain unidentified, but they could easily belong to customers who entered the shop in the days leading up to Mr Newbery’s death, a statement said.

Mr Newbery suffered four or five blows to the head with a large blunt object that was never found. One blow, to the left side of the skull, probably knocked him unconscious and was probably the fatal blow, court documents stated.

Mr Newbery’s face and shirt were covered in blood and the blows were of such force that blood and other matter were found metres from the body.

‘‘[Mr Newbery] may have struggled with his attacker or attackers,’’ deputy state coroner Mr Buscombe said.

‘‘He was a long-time resident of Newcastle and ran the business for 58 years.’’

‘‘I urge anyone with information to come forward.’’

A $100,000 reward for information still stands.

Call Crime Stoppers on 1800333000.