Marvyn Iheanacho has been sentenced for a minimum of 18 years in prison Pic: Met Police

A man who beat his girlfriend’s young son to death in Catford for losing a shoe has been jailed for life.

Marvyn Iheanacho brutally battered five-year-old Alex Malcolm in November of last year during a visit to Mountsfield Park. Witnesses heard a child’s “fearful voice saying sorry”, loud banging and a man shouting about a lost trainer.

Judge Mark Dennis sentenced Iheanacho to a minimum of 18 years in prison today saying he had a “deeply entrenched character flaw” that “leads [him] to overreact and lose [his] temper”.

He “used [his] undoubted strength and simple brute force,” against a “completely defenceless” child, Dennis added.

Police later found the missing trainer in a nearby play area.

The 39-year-old from Hounslow had been dating Malcolm’s mother, Lilya Breha, since June and would often stay in her Lewisham home.

Iheanacho took the unconscious boy to Breha’s flat after the attack and assaulted her when she tried to call an ambulance.

“His face was disgusting,” Breha said as she described the fatal head and stomach injuries suffered by her son.

She said she started screaming when she saw Malcolm and repeatedly shouted ‘What have you done?’ at her partner.

Breha told the jury at Woolwich Crown Court on Friday that Iheanacho tried to strangle her when she called for help after noticing her son had stopped breathing and his face had turned blue.

The boy was transferred to King’s College Hospital after scan results at Lewisham Hospital revealed traumatic brain swelling. He died two days later after an unsuccessful operation.

Iheanacho denied the murder and offered several explanations of how the shocking injuries were caused, including that Malcolm fell from a climbing frame in the park.

Detective Chief Inspector Tony Lynes said Iheanacho flew into an “uncontrollable rage” just because the boy lost one of his shoes and it was “no surprise the jury easily saw through his stories”.

The jury was shown a note from Iheanacho’s diary, where he admitted  beating the boy in a previous incident for “sicking up in the cab”.

The diary reads: “Do I really love Alex, five years old small cute lil boy.

“Who want nothing more, than daddy mills to love him protect him but most of all keep him from harm – even though I had to beat him just now for sicking up in the cab – why why why I say – so the answer is yes yes yes I love him and like with all my heart but may not enough.”

The jury of five women and seven women announced a unanimous guilty verdict.

Breha nodded and quietly wept as the verdict was announced.

She said in a statement: “Alex was so small but he was my strength and my purpose for living. The hardest thing I have ever had to hear was that my child died. I remember it like it was yesterday.

“Lying next to him in a hospital and praying that everything would be fine, that he will open his eyes. I didn’t even get to tell him I love him. All I got was to put my hand on his chest and feel every single one of his final heartbeats.”

Iheanacho has a string of previous convictions for violent offences, including six convictions for domestic abuse.

District Crown Prosecutor, Rob Davis said: “Only Marvyn Iheanacho knows how Alex was fatally wounded but it is certain his anger boiled over at some point on that evening.

“His actions that day tragically ended a young boy’s life and deprived a mother of her son.

“His efforts to cover up what really happened, first to Alex’s mother by claiming Alex had simply fainted and hit his head, then by lying and repeatedly changing his story to police show his greatest concern was for himself.”