A janitor accused of molesting two sisters never worked at a high school where one of the women said she was touched inappropriately, a court has heard.
The jury in the ACT Supreme Court trial of Lazo Djenadija, 75, retired to consider their verdict on Thursday.
Djenadija is accused of four crimes against the two sisters, then aged between nine and 12, in the 1980s.
The pair were in his care and often attended his Canberra home.
The older sister alleged she was molested in a gym storage room at Melrose High School, saying Djenadija took her there after hours.
But the Crown was forced to concede to the jury on Thursday that Djenadija had never worked at the school.
The defence, led by barrister Richard Thomas, used the error to cast doubt on the veracity of the rest of the elder sister's story.
In the Crown's closing submission to the jury, it was argued the mistake was not significant or surprising.
The complainant was young, prosecutors said, and may have subconsciously replaced the now-closed Woden Valley High School, where Djenadija did work, with Melrose High School in her memory.
The two sisters were described as "reliable and truthful witnesses" who, despite having never talked to each other in detail about their experiences, gave strikingly similar accounts of the words Djenadija allegedly used during the acts.
It is alleged the younger of the sisters was indecently assaulted on two occasions on a bed in Djenadija's home.
He is accused of rubbing himself against her groin and making her touch him.
On one of the occasions, the younger sister said Djenadija's girlfriend interrupted them, and her abuser quickly got up and pretended he was playing a game with her.
The former girlfriend was called by the defence on Thursday, saying she never saw anything of that nature.
In cross-examination, the Crown put to her that she regularly saw Djenadija playing with the girls, so such an incident wouldn't have stood out in her mind.
She replied: "I think it would because I'd want to know why he was in that room.
"Even when I was in my early 20s I'd still have my suspicions about why he was in there with another girl."
She also gave evidence that there was no VCR in the home, contradicting evidence that the sisters were forced to watch pornography.
The jury will begin deliberations on Friday in the ACT Supreme Court.
Chief Justice Helen Murrell concluded her summing up of the case on Thursday afternoon.