A mum murdered two of her children because she feared social services would take them into care.
Sarah Barrass, along with family member Brandon Machin strangled Tristan and Blake Barrass, aged 13 and 14, in Shiregreen, Sheffield, on 24 May.
The court heard how Barrass, 35, would regularly tell her children: “I gave you life, I can take it away.”
Barrass and 39-year-old Machin are being sentenced at Sheffield Crown Court.
The court was told they had unsuccessfully tried to poison their four eldest children the night before, by forcing them to take ADHD tablets.
Kama Melly QC, prosecuting, said: “None of the children wanted to take the tablets but were forced to do so.
“The defendants expected the tablets to kill the children overnight.”
The court heard after the bid failed, Barrass strangled Tristan with her dressing gown cord.
Machin then strangled Blake with his hands.
They “then placed bin bags over their heads to ensure their certain death”, Ms Melly said.
Barrass and Machin have both previously admitted murder, conspiracy to murder all six of her children, including Blake and Tristan, and five counts of attempted murder.
All the surviving children, who cannot be named for legal reasons, are under the age of 13.