Their son Alexander James William Merritt, 21, is on trial charged with the murder of Spotless Cleaning Services supervisor Karin Ann Ross.
The victim was found face down in a pool of her own blood in the carpark of the business on Strathallan St by fellow staff member Mrs Merritt in the early hours of December 2 last year.
Ambulance officer Annabel Taylor was first on the scene and said the scene seemed "strange".
"There was blood everywhere from her upper torso to over her head," she said.
"It looked like a crime scene."
Two days later, police inquiries led them to the Merritt family house on Nairn St where they allegedly found blood in the bathroom and the blood-soaked items in the yellow-topped bin outside.
Crown prosecutor Richard Smith said at the trial's outset that forensic testing of the blood had shown it was one million million times more likely to belong to Ms Ross than anyone else.
The jury was shown a black hooded top with a blue "35" printed on it, a dark glove and a hammer.
Mrs Merritt, who spent more than a day in the witness box, said none of them looked familiar to her.
But she believed a pair of black shoes shown to her could have been like ones worn by her son.
The Crown had earlier said investigators found blood spatter on shoes taken from the defendant when he was arrested on December 9, 2015.
A pathologist is expected to give evidence that Ms Ross sustained 14 "dramatic and extensive" injuries to her head and 32 separate bruises to her hands and arms.
After being spoken to by police on the morning she found Ms Ross dead, Mrs Merritt said she returned home to find the washing machine on and the defendant in the kitchen.
Mrs Merritt told the jury her son was getting band aids out of the cupboard and she did not see his face until the next day.
She noticed scratches to his forehead and asked what had happened.
"He said he scratched himself in the night," Mrs Merritt said.
"He had eczema, so he used to scratch himself a lot."
But during his opening, prosecutor Mr Smith said the jury could infer Merritt's injuries came during a struggle with Ms Ross.
DNA samples taken from under her fingernails turned up cells 430 times more likely to belong to the defendant than anyone else, he said.
The trial continues.
Jury viewing
Today the jury of eight men and four women will be taken to the Strathallan St carpark where Ms Ross was found dead.
The group, which will travel on a bus with a police officer and court registrar, will then travel to the Merritt family home on Nairn St in Kaikorai.
Justice Nicholas Davidson said he and the lawyers would also attend but there would only be "limited communication" between him and the jury foreperson.
The purpose of the view was so jurors could familiarise themselves with the scene, which would help when photos were referred to in court, he said.
Justice Davidson told them Merritt would not be there and also declined the Otago Daily Times' request to attend.
