"He has been wrongfully accused, anyone who knows the guy knows he did nothing but look after that baby," he said.
"He's known him since he was three months old… he loved that boy."
The brother revealed details of what he believed happened on the day police allege Malcolm suffered the fatal injury.
The boy's mother Savanna Bell left him with the accused while she went to work.
"She was gone about 15 minutes and (the accused) went to the toilet and came out and the boy was having a seizure," he explained.
"He stopping breathing, my brother tried to revive him, he called Savanna and told her to come home… then the ambulance came."
The brother said police had charged the accused because he was alone with Malcolm when they believe the injury was inflicted.
However the accused told his brother that the boy had been sick much earlier in the day, refusing food and water and "looking unwell".
"He was the last person with the baby - but he was always the one with the baby," the brother said.
"My brother loved that baby… I've never seen him touch a kid, never seen him hit a kid, he's not that type of person.
"My brother looked after my kids when they were babies, he brought up one of his own sons who was taken off the mum.
"He's just distraught, he is horrified he has been charged."
The brother said Malcolm was a lovely child and his death had been devastating.
"He was so good, he was full of life and full of energy," he said.
"When my brother found out he had died, he just broke down… I can't believe it… he cared a lot about that baby. "
Malcolm died on June 29, sparking a homicide investigation.
Police were focused on two people - the accused and Savanna Bell.
Up to 20 officers worked on the investigation and today Detective Senior Sergeant Geoff
Baber confirmed that an arrest had been made.
The Herald understands police were focused on just two people.
"Today's arrest is the result of countless hours of work by a team of investigators who
have investigated this child's tragic death," he said.
He could not comment further as the matter is now before the courts.
Earlier Baber said police were alerted to Malcolm's injuries by hospital staff who believed he had been deliberately harmed.
Malcolm has five older siblings who have all been removed from his mother's care by Oranga Tamariki.
All five children are currently in the care of others.
Savanna Bell has refused to speak to the Herald.
"I have had legal advice and I will not be speaking to the media," she said in June said when approached for comment.
Her Facebook page, deactivated after her son's name was released following his death, had numerous posts about Malcolm.
"Watching you grow makes me so happy," she wrote.
"Your first word was mama I was so happy when I heard you say mama.
"You have an awesome personality my son Malcolm your (sic) growing every single day and night ... I love you always my son."
