Sarah Barrass and Brandon Machin admitted murdering Blake and Tristan Barrass, aged 14 and 13, who died after being found critically ill at a home on Gregg House Road in Shiregreen in May.
The pair also admitted attempting to murder Blake and Tristan plus two of her other children and conspiring to murder all six of Barrass’ children, the other four of whom are aged under 13.
Sarah Barrass’ brother Martyn Barrass claims he contacted social services a decade ago asking them to look into the duo, who he said had been ‘evil since birth’.
Speaking to the Sunday People, he said: “I witnessed Brandon’s violence towards Blake years ago and I knew something wasn’t right. I visited them when Tristan was still in his pushchair and Blake was only a toddler – he must have been three or four.
“We were out walking when Brandon grabbed Blake’s arm really roughly and dragged him across the floor.
"It was enough to know something wasn’t right, so I called social services and asked them to look into it. If they had, the boys might still be here today.”
Mr Barrass told the paper he made three phone calls to social services, urging them to check on his nephews, in 2009 or 2010.
“I told them about the incident. I was told they would look into it, but I didn’t hear back from them. I feel like I was ignored,” he said.
“It felt like I wasn’t listened to. Our world has been ripped apart. I’ve lost my little nephews.”
The 34-year-old, who lives in Wirral, Merseyside, described Blake and Tristan as ‘polite, kind-hearted lads’ and told how he believes their deaths could have been prevented.
“Social services have been aware of our family since before Sarah had kids. They don’t seem to have done the job they could have done or should have done. That’s what I’m struggling to understand,” he told the Sunday People.
"The main people to blame are Sarah and Brandon. But social services could have prevented it, could have stopped it. This will haunt us forever.”
Sheffield Council announced in the days following the boys’ deaths that a serious case review would be held, looking at the circumstances surrounding the tragedy.
Councillor Jackie Drayton, cabinet member for children and families, said at the time: “All partners in the city will be coming together to understand, review and reflect on exactly what happened and why.
“Over the coming weeks and months the Sheffield Safeguarding Children Board will be working with partners to instigate the serious case review procedures. All information about this case will be covered in its findings.”
John Macilwraith, the council’s executive director of people services, said: “We have initiated the review but detailed work will start once the legal process has completed. It is important we do not compromise any court proceedings.”
Sarah Barrass, 35, of Gregg House Road, Shiregreen, and Machin, 39, of Burngreave Road, Burngreave, who is a family member, appeared at Sheffield Crown Court on September 27, when they admitted two counts of murder, five of attempted murder and one of conspiracy to murder.
They are due to be sentenced on November 12 and have been warned they could face life behind bars.
There is a reporting restriction in place which prohibits the press and public from identifying Barrass’ four surviving children by name.
Police were called to Gregg House Road on the morning of May 24 this year, after receiving what they described as ‘reports of concerns for safety’.
All six children were taken to hospital, where Blake and Tristan died later that day.
The cortege was led into the grounds by 300 bikers and two Lamborghinis, reflecting the boys’ love of fast cars and motorcycles.
Vicar Lisa Scott described Blake as a boy who really loved his football, wore his heart on his sleeve and always made people feel loved.
Tristan on the other hand wanted to be different, she said. Mischievous and lovable, his multi-coloured hair got him in trouble with his teachers, she added, but he would always make you smile.
Family friend Danielle Baines described the brothers as ‘two beautiful boys who touched the lives of everyone they knew’.
She said: “Blake had a natural ability to make everyone smile even if they were having a bad day. He cared about everyone and he had such a big heart. Tristan was brave and knew exactly who he was. He did what he wanted to do no matter what anyone thought. And he loved to express himself through his clothes.”
“Both of them were amazing and I can’t describe how proud I was of them. I think that is how we should remember them.”