Leroy Malcolm said he had struggled to watch killer Marvyn Iheanacho lie throughout his trial for the murder of Alex Malcolm and has suffered depression ever since, adding he had been denied access to his son before his death because he 'had a better man in his life'.
Iheanacho, 39, battered his girlfriend Lilya Breha's child to death in a park in Catford, south-east London, for losing a shoe.
He attacked with such savagery that witnesses who overheard eight 'booming' blows initially thought two grown men were fighting. They heard the child begging for mercy, sobbing, 'I'm sorry, I'm sorry.'
Instead of taking the dying boy to hospital only a five-minute walk away, Iheanacho carried him through the street before taking a cab to his mother's home in Bromley, south-east London, where he attacked her, throttling her as she tried to call 999.
When Miss Breha managed to raise the alarm two hours later, doctors were unable to save the youngster, who had 22 bruises from head to toe. He died two days later following a bleed to the brain.
Iheanacho was jailed for life at Woolwich Crown Court today with a minimum sentence of 18 years imposed.