"We noticed feet out the bottom of the bed [the woman] was in. They were underneath the blanket."
He said the positioning of the feet indicated the person was on top of the woman, and he noticed a pair of shorts around the ankles, but he could see no movement.
"I remember thinking it was strange and I was, I suppose, a little shocked and surprised about it and confused."
He left the room again but, reflecting on the drunken state the woman was in when she went to bed, he soon returned and found the woman alone.
She was shocked to hear about it the following day, he said.
"Shock and confusion, I suppose, would be the best way of describing it. She was wondering why she woke up with no pants on," he said.
During the trial the woman described feeling "scared and violated" as she grew to understand what had occurred while she lay sleeping.
She called her parents who took her to the police station to make a statement, and then a medical centre where she was forensically examined by a doctor.
About a year ago she was informed Tehuna's DNA profile corresponded to that taken from her clothing and internal swabs in 2003. He was, and still remains, unknown to her.
Although the DNA didn't initially correspond with any stored on the national database at the time of the offence, Tehuna was arrested in 2015 and a sample of his DNA obtained.
Crown witness, Institute of Environmental Science and Research (ESR) forensic scientist Susan Vintiner, confirmed there had effectively been "a hit", as described by Crown prosecutor Steve Manning, in the National DNA Databank.
Yesterday Tehuna took the stand to defend himself but the jury was unconvinced and returned with a unanimous guilty verdict after deliberating for about four hours.
His partner, mother of their 2-month-old baby, sat alone in the public gallery to support him.
He was remanded in custody for sentencing next month.