Jeffrey (19) was the Hannons' eldest son.
He was found beaten to death just yards from his parents' home in Southill, Limerick, on November 22, 2007.
As the heartbroken Hannon family prepares to mark the fifth anniversary of Jeffrey's death, his father has asked for those with information to go the gardai.
Alan Hannon said: "The parents of the main suspect know what their son has done. If that was my son I would be up to my garda station straight away and I would hand him over to them."
He added that the garda investigation into his son's murder has run cold.
"There's been nothing," he explained.
"Everyone knows who has done this and there's nothing we can do. The gardai say there isn't enough evidence to charge anyone."
Jeffrey Hannon was an innocent victim, gardai believe.
The murdered teenager had no involvement in criminality.
It's believed he was set upon by another young man after he left a house party in Southill.
Jeffrey's body was discovered lying in a green area at the rear of his parents' house.
He had been bludgeoned to death with a blunt implement.
The small, tight-knit community of Galtee Drive in Southill, where the Hannon family live, were shocked to hear who had been the victim of such a severe assault.
Residents said Mr Hannon was a quiet young man who had become a father a year previously.
The chief suspect for the murder is serving a life sentence in jail after killing a man in a gun attack in Limerick.
Around a dozen people have been arrested by gardai investigating Jeffrey Hannon's murder but no one has ever been charged with the killing.
"The heartache continues every year," said Alan.