The family of a 76-year-old man who was murdered in his home have offered a £10,000 reward for information on his death after the case against a suspect was dropped.
It comes after the Crown Prosecution Service (CPS) dropped its case against suspect Elemer Patakfalvi.
The 47-year-old was arrested and charged last December with the murder of Karoly "Charlie" Varga after he was found dead in his home.
But following a review, the CPS has now decided to drop the case against Mr Patakfalvi.
Mr Varga, known as Charlie to his friends, was found at his home in Cannon Street, Wellingborough, on July 30 last year.
He had died from head injuries inflicted by a bladed weapon.
The murder weapon has never been recovered.
Northamptonshire Police have re-released CCTV footage from the day of the murder, which shows a man entering Mr Varga's home, in the hope it will help trigger someone's memory.
Rita Groves, Mr Varga's daughter, said: "We are aware the police have worked hard to detect our father's murderer and it is disappointing that they have not yet been able to convict the person who robbed us of him.
"Our father was a kind man, who was no threat to anybody and we cannot understand why anybody would want to attack him in this way.
"We have put forward this reward in the hope it will encourage anybody who has any information to come forward.
"We know the murder weapon is still missing and we hope this reward will encourage people in Wellingborough to check around their properties in case the weapon, the Lonsdale trainers or clothing left by the offender are still laying somewhere, waiting to be found."
Detective Chief Inspector Martin Kinchin, who is leading the murder investigation, said: "It is likely that Charlie Varga was killed on Wednesday 27 July 2011, sometime after CCTV footage shows him letting a person into his house.
"We can see from the footage that there were a number of people passing at that time who may have seen that visitor - I want to speak to those people.
"We also know that Charlie's killer left via his back gate into Bell Street and Bell Court. That person had with them a small, potentially axe-like weapon which would have potentially been lightly blood stained.
"That murder weapon has never been recovered and potentially is still lying wherever it was hidden.
"I can also now reveal that the offender was wearing Lonsdale training shoes at the time. These shoes would have been bloodstained and so again would have been disposed of or hidden somewhere in Wellingborough.
"There is a chance that somebody has found the discarded weapon in their garden and simply put it in their shed, unaware of its significance, or somebody knows where a pair of Lonsdale trainers lie discarded on waste ground and it is hoped the reward will encourage people to come forward."
Anybody with information is urged to contact Northamptonshire Police on 101, or call Crimestoppers anonymously on 0800 555 111.