Grandfather Anthony Bird, aged 50, died a fortnight after the attack, which happened in front of horrified families in Victoria Park, Tipton, on a Sunday morning in July last year.
He was taken to hospital but his condition deteriorated and he died before being able to meet his second grandson.
Steven Bennett and Suni Singh Gill rained punches and kicks on Mr Bird after accusing him of being a “convicted paedophile,” a claim which was completely unsubstantiated.
The pair were found guilty after four hours and 13 minutes of deliberation by the jury in unanimous verdicts following a trial at Wolverhampton Crown Court.
They will be sentenced at the court on Wednesday.
Mr Bird had five adult children. In the aftermath of the verdicts, they released a statement which said: “We have to live with the memory of visiting our dad in hospital following the violent attack on him last summer. It was huge shock to see how badly beaten dad had been and it is a memory that we are worried will stay with us forever.
“Our dad was an extremely caring and kind man. He was very proud of his children and was over the moon to be a grandfather. Sadly he never got to meet his second grandson who was born a month after he was killed.
“We will never understand why anybody would want to take our dad’s life in such a brutal manner. We can only hope and place our trust in the justice system to punish those responsible accordingly.”
Mr Bird, known locally as "Goughy," died in hospital 17 days after the attack as a result of blunt force head impact, with a background of serious pre-existing liver disease which impaired his blood clotting.
Bennett, 38, of Bevan Road, and Gill, 33, of Shore Road, both Tipton, had both denied murder.
The court heard that the pair did not know Mr Bird, who had been walking through the park at the time of the attack on July 26. They turned on him after a female companion told them that Mr Bird had taken a photo of her children.
A witness told the jury that Gill was the first to attack Mr Bird, followed seconds later by Bennett with continuous kicks. They carried on kicking him despite being urged to stop.
Mr Bird was seen to stagger out of the park while stunned onlookers phoned 999 to report the attack.
Bennett claimed to only punched Mr Bird once, while Gill claimed he was drunk and had mental challenges and could not recall all of what happened.
Consultant neuropathologist Mr Daniel Du Plessis told the court that the injuries from the attack were, in isolation, life-threatening but survivable. But the bleeding on the brain then doubled, he developed a chest infection and his organs failed.
Judge Michael Chambers QC told the jurors: "This particular case was very serious and disturbing because it took place in public on a Sunday morning at 11am and in front of children.
"This is the end of your role in this tragic case. Thank you all. If you wish to return for the sentencing you are welcome to do so.
"We recognise that you have carried out your role responsibly."
He added that the panel had been acted "patiently" and "conscientiously" throughout the proceedings.