The sister of a man murdered after buying a pizza from a fast food shop said a 12-year-old boy has been left without a father.

Paul Mathieson was killed after being found with serious head and facial injuries on Wilson Street in Renfrew on Sunday, January 14.

Mr Mathieson was taken to hospital in a critical condition but later died on January 20.

The 37-year-old bought a pizza from a nearby fast food shop before the attack, having previously been in the Western Bar and the Kind Man's on Hairst Street.

In an emotional appeal, his sister, Amanda Digby, said her brother's death has left "a massive gap" in their family's lives.

She said: "Paul was an average young man but so special to us. He was a brother, a nephew, an uncle, a grandson and a father.

"His murder has left a 12-year-old boy without a dad.

"Paul left that night to go for a few drinks, however, he never returned and we never saw him alive again.

"His death has left a massive gap in our lives."

CCTV footage shows Mr Mathieson talking to another man in Wilson Street.

Officers said the man is then seen punching him to the ground before striking him several times and running off towards Houston Street.

Ms Digby said: "We are devastated at what has happened.

"No one ever thinks that this will happen to them, we thought that too and we are still desperately trying to make sense of it.

"I just want to ask people, please, if you have any information about the crime or the person responsible, please speak to the police and pass on this information, even if you think it's not relevant, still tell the police."

Ms Digby continued: "Imagine if you were in our position, you would do everything you could to find out why your loved one has been taken away.

"It's in all of our interests to find the person responsible for my brother's death so please help us and contact the police."

Chief inspector Martin Fergus said: "Paul is an individual who drank in Renfrew town centre regularly in the local public houses.

"That evening, we believe he went out alone and joined the company of various individuals.

"A lot of those individuals were traced and spoken to but there are other people out there clearly - it was a Saturday night in Renfrew - there's a lot of people using the public houses, the restaurants.

"We're really keen to piece together Paul's movements, who he was with, did he have an argument with anybody that night, was there animosity between him and anyone in the public houses or in the takeaways that he attended.

"If anyone has any information relating to that please contact us as soon as they possibly can and let us be the judge of how important that information may be.

"Our early enquiries would indicate that potentially they knew one another however we can't rule out that it could have been an individual passing by."