It was possible for Mortimer Saunders' semen to have been present in Courtney Pieters' body, even if he had not raped her, the Western Cape High Court heard on Thursday.
Forensic analyst Lukhanyo Tiya, who was cross-examined again after an application by the defence, confirmed that, while pre-ejaculation fluid is produced before semen, it was possible to find semen in the fluid if the man had ejaculated more than once.
Saunders had in his plea explanation admitted to killing the toddler, but denied having penetrative sex her.
He admitted to pulling down her shorts and panties and confessed to using his fingers to penetrate her. He said he became aroused and put his penis around her vagina.
Death not planned
He could face life imprisonment if convicted of raping a minor.
Saunders faces charges of premeditated murder and rape, but denies that the toddler's death was planned or that he had sex with her while she was alive.
He admitted that he had given Courtney ant poison to make her sick, before he choked and beat her and used a towel to close her mouth.
He claimed he had done it because of "ill feelings" between him and Juanita, the toddler's mother.
Saunders - a childhood friend of Courtney's father who lived in the same Elsies River house - had also ostensibly been irritated because the little girl had wanted to watch TV in his room, and he had wanted to sleep.
Additional tests
Defence advocate Mornay Calitz asked if all the initial presumptive test results had been subjected to DNA analysis.
Tiya said it had not as, in some instances, lab staff had not known what fluid to search for.
Calitz pointed out that, only in April this year, a request was made by prosecutor Esmeralda Cecil for additional tests.
"You leave certain samples for almost a year. Then when State counsel asks for additional tests, you only then do it," he said.
Tiya said the laboratory followed standard operating procedures, which dictate that the employee needs to know for sure what bodily fluid is on the sample.
He said there was "nothing sinister" about it.
Pieters' body was found in Epping Industria, nine days after she went missing in May last year.
Calitz asked about the effect of decomposition on DNA, and Tiya explained that it becomes degraded. "You have a better chance of getting results from a fresher sample," he said.
The trial continues on Tuesday, when a pathologist is expected to testify.
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