A Dunedin cleaner beat his boss to death with a hammer because she had complained about his conduct at work, the Crown says.

Alexander James William Merritt, 21, is before the High Court at Dunedin charged with the murder of 51-year-old Karin Ann Ross.

The victim was found face down in a pool of her own blood by the defendant's mother, who also worked at Spotless Cleaning Services on Strathallan St, on December 2 last year.

Ross had "dramatic and extensive" injuries to her face, the court heard this afternoon.


Crown prosecutor Richard Smith said Merritt had attacked Ross with a hammer but there was evidence she had fought back and tried to escape.

When police arrived at the scene they found a white van, which had been driven by the victim, up against a skip.

There was blood inside the vehicle and a bloody hand print on the outside, Smith said.

The Crown said no motive had to be proven but in this case Merritt had made his hatred of the victim clear.

"I would like to burn her family in front of her," he allegedly told one colleague.

"That lazy b****. It would be fine if she died," the Crown said he told another.

Police at the scene in Strathallan St in December. Photo / Stephen Jaquiery, Otago Daily Times
Police at the scene in Strathallan St in December. Photo / Stephen Jaquiery, Otago Daily Times

Ross had recently cut the defendant's hours at the business and days before the alleged murder, Merritt had been informed of disciplinary proceedings being initiated against him.

He had continually parked in a disability spot and was censured for his behaviour around other staff, Smith said.


The day before he allegedly attacked Ross, he had received a statement from her and another staffer in which they outlined their concerns about his conduct.

Once Merritt came to police attention an extensive search of his family's Kaikorai home on Nairn St took place.

Forensic investigators found blood on the neck and spout of a bathroom tap and on bathroom cabinets.

In a wheelie bin outside there was allegedly a blood-soaked hammer wrapped in a similarly bloody shirt.

Scientific analysis of the items found the DNA one million million times more likely to belong to Ross than anyone else.

When police questioned Merritt on December 4, 2015, they asked why he had scratches on his face.

He told them he had scratched himself in his sleep.

"You can infer they were made by Karin Ross as she fought for her life," Smith said.

Defence lawyer Anne Stevens said her client went home from work on the night in question and never left.

Cellphone tower data that placed him away from his home at 1.34am would be strongly challenged, she said.

The defence took a similar view of the scientific evidence, which Stevens said contained "surprising gaps".

The trial before Justice Nicholas Davidson and a jury of four women and eight men is scheduled to last two weeks.