This is according to a source close to the investigation into the rape and murder of the little girl.
Saunders is back in court on Thursday, where he faces two charges of rape and one of murder.
Courtney went missing on 3 May, and following a nine-day search, her tiny body was found buried in a shallow grave at Bofors Circle, Epping Industria.
The 40-year-old suspect is being kept in the hospital wing of Goodwood Prison.
At his last court appearance, Prosecutor Adnaan Gelderbloem said DNA tests, forensic reports and witness statements would be ready when Saunders appears in the Goodwood Magistrate's Court on Thursday.
Saunders was the childhood friend of Courtney’s father, Aaron Fourie, and was boarding with the family in Salberau Estate when the child was killed.
The source reveals that during interviews with investigators, Saunders said on that fateful Friday morning, he had just wanted Courtney to be quiet.
SEEKING JUSTICE: Saunders will be returning to court today
“He said he was tired and wanted to rest after a night shift at the call centre where he worked,” says the source.
“He had gotten into bed after 8am when she came in, jumping on the bed and she switched the TV on. He asked her a few times to go out and she ignored him.”
That is when Saunders allegedly gave Courtney Fusion cooldrink spiked with ant poison.
Apparently, the first cup went down easy, but he struggled to get her to drink the second cup.
“Mortimer said she was fussy and when the other kids called her, he choked her and she ‘passed out’. He covered her with the duvet and the kids came in the room looking for her. They could not see her tiny form under his covers,” says the source.
‘I WAS TIRED’: Mortimer Saunders, accused of killing little Courtney
When the children left and he lifted the duvet, “he was surprised to see Courtney was blue in the face”.
“He told me he never wanted to kill her.”
On Wednesday mom Juanita Pieters, 42, said all she wants to know is what really happened to her child.
“He must tell me what he did and why. I will be at court every day until I get my answers,” she says.