Toddler Brandon Muir died after being assaulted by Robert Cunningham, 23, in Dundee last year
Sentencing Cunningham at the High Court in Glasgow, Judge John Morris told him he must spend 10 years in jail.
Responding to the term outside the court, the child’s grandmother Veronica Boyd said: “It’s not enough. He has stolen and taken our grandson from us.
“He has caused total devastation to both sides of Brandon Muir’s family.
Brandon died from a ruptured intestine following an attack by Cunningham at the flat on Balunie Crescent he shared with the toddler’s mother Heather Boyd, 23.
A lengthy trial which heard from more than 50 witnesses heard how Cunningham punished the youngster for climbing on to a window ledge by forcing him to stand at a wall.
The jury agreed with prosecutors that he applied pressure to the child’s abdomen “by means unknown” which led to his organ damage and death.
The child was severely ill and vomited in the hours after the assault but drug users Cunningham and Boyd failed to get medical assistance.
Boyd was originally charged with killing her child along with her partner but was acquitted during last month’s trial.
The jury also rejected a charge of murder against Cunningham. The case sparked a review of child protection services at Dundee City Council as it emerged that social workers had been alerted to concerns over Brandon by family members and neighbours.
Cunningham has two previous convictions for dishonesty and failing to turn up at court, it emerged today.
Exclusive – Brandon Muir’s killer Robert Cunningham had history of torturing children
TWISTED Robert Cunningham was a cowardly thug who had a history of torturing children.
The 23-year-old jobless heroin addict had also been linked to sex attacks on women and stood trial for rape.
He was twice accused of flashing, although only ever convicted and given prison time for housebreaking and breaching bail.
Friends and former associates describe him as a bully who got his kicks preying on those weaker than him.
But he was left sobbing in fear when confronted by someone as strong as him.
After getting into a brawl with a neighbour, Cunningham lost a shoe and limped round to a friend’s house in tears.
The friend said: “It’s not like the guy hit him that hard but he was a wimp when it came to fighting with anyone his own size.”
Children bore the brunt of Cunningham’s brutality – with 23-month-oldBrandon Muir dying at his hands.
A former pal of Cunningham saw him throw a toddler so hard against a cot that it smashed.
Another said she saw him blowing in the face of a newborn baby because he thought it was funny when the child struggled to catch a breath.
On another occasion, Cunningham screamed in the face of the same baby because he was livid it was crying.
He called one toddler he was in contact with b*****d so often that the child thought that was one of its names.
His victim will now cover its ears whenever there is any loud noises or talking.
Another friend was shocked when she saw him throw a child against a table.
The woman said: “He belted the kid and the kid was screaming.
“It was horrible. Robert would just lose it.”
A child who touched a cream couch where Cunningham was living was punished by being made to sit on the floor with his hands crossed on his lap for three hours.
If the child moved, Cunningham would lash out.
The toddler was left so traumatised that, from then on, he would only touch the couch with the back of his hands.
In court, the girlfriend Cunningham was involved with before Brandon’s mother said she often fought with him over the way he treated a child.
She described how he would smack the child if he was bad, shout and swear at him, put him in his bedroom or make him sit beside a wall.
She said Cunningham would make him sit against the wall for 20 or 30 minutes at a time.
He would also make the child sit on the floor for two to three hours because he was “angry”.
When the child cried, he would taunt him and call him a cry-baby.
He thought that it was funny when the toddler got upset.
But – perhaps through fear of retaliation – none of the people who witnessed his behaviour towards youngsters informed the police.
It was a different story in 2005 when he stood trial for raping a teenager.
She had accused Cunningham – then 18 – of attacking her on September 16, 2003, in a flat in Dundee‘s Balunie Crescent. It was the same street in which Brandon was killed.
The victim claimed Cunningham grabbed her, forced her to kiss him and straddled her as he stripped her naked then raped her.
He failed to appear at the High Court in Edinburgh on May 7, 2004, and a warrant was issued for his arrest.
But police had no idea where he was.
When the case called again at the High Court in Forfar the following month, he also failed to show and the warrant was extended.
Detectives finally caught up with him and he appeared back in Edinburgh on March 30, 2005, when he faced two charges – one of rape and one over the bail violation.
Cunningham’s trial started on May 16, 2005, in front of Lord Hardie at the High Court in Dundee. It lasted three days.
The witnesses included police officers and medical experts but a jury decided that the case was not proven.
However, Cunningham was sentenced to six months’ jail for the bail offences.
Later the same year, he was the chief suspect in two sex attacks on young females.
Tayside detectives hauled him in for questioning over allegations that he twice exposed himself to youngsters while sitting on a bike.
But he was never arrested or charged and the cases were dropped.
In February 2006, Cunningham received a hefty community service order for breaking into a house in Dundee.
He was collared for the same offence less than 10 months later and jailed for three months.
Last night, a police source said: “Cunningham is well known to our officers. He has been for some time and he is never far from trouble.
“He has a significant heroin addiction and his housebreaking in 2006 was undoubtedly to fund his habit.
“We’re pretty sure he’s been involved in a fair amount of minor criminality across Dundee over the last few years to help him acquire drugs.
“We’ve also come across him during various domestic disputes but nothing severe enough to warrant us taking further action.”
With Cunningham dishing out beatings and abuse behind closed doors, his victims were often too scared to press charges.
Ex-girlfriend Nikita Bowman, 19, was terrorised and regularly beaten by Cunningham when they were together.
He punched her, kicked her and held her down by the throat.
They started dating when she was only 13 and Cunningham was 18.
She said he treated her relatively well at first.
After a few months, they split up but got back together when she was 16. It was then that she saw a very different side to him.
She said: “I was scared what he would do to me. He would just lose the plot and hit me.
“I was really frightened of him.
He was evil.”
On one occasion, she had to jump out of a window to escape after he shoved her into an empty bath and pinned her down by the neck.
Nikita said: “I don’t even know what started it but he just went nuts. I thought he was going to kill me.”
She got used to regular beatings, sometimes a whack on the arm, at other times a kick in the stomach.
At the flat they shared, he smashed all the doors from their hinges.
But despite the kick he got from abusing women, Cunningham fancied himself as a ladies’ man.
He had sex with Brandon’s mum, Heather Boyd, in the flat he was sharing with Nikita when she went to the shops.
He also propositioned Nikita’s sister, Cheyanne, when they were all at the same party.
Cunningham threatened to sexually assault her while she slept.
Cheyanne said: “He was really dirty and sleazy.
“He said I should go to to bed with him and when I told him he was a disgusting pig, he said he would wait until I was asleep and feel me up.
“I hated him. He was evil. I’m not surprised he killed Brandon and I hope he rots in hell.”