The Crown says a Dunedin cleaner beat his boss to death after dragging her out of a vehicle in which she had tried to escape.
But the lawyer for Alexander James William Merritt (21), Anne Stevens, argued there was no evidence he was even at the Strathallan St premises of Spotless Cleaning Services when the fatal attack on 51-year-old Karin Ann Ross took place early on December 2 last year.
Ms Stevens said her client, who has been on trial before Justice Nicholas Davidson in the High Court at Dunedin for more than two weeks, was an "easy target'' for police because he had clashed with the victim at work.
"It's literally a whodunnit,'' she told the jury.
"Police decided early on it was Mr Merritt. He was their suspect when they looked for their evidence.''
But Crown prosecutor Robin Bates told the court in his closing address there was more than enough evidence for the jury to be sure of the 21-year-old's guilt.
He said the attack against Ms Ross was "unrelenting'' and there was evidence that she had been struck at least once while she was on the ground.
"Spines'' of blood radiating from the victim's head where she was found face down proved that, he told the court.
With 14 blows to her head and 32 defensive wounds to her hands and arms, the killer's intent was clear, Mr Bates said.
Her blood in a van, found crashed into the skip, showed she tried to escape. The prosecutor pointed to a bloody gloved handprint allegedly from when Merritt dragged her out of the van, closed the door and continued the attack.
Ms Stevens said blood at the scene had not been tested and was highly critical of the police's assumption it all belonged to Ms Ross.
"What about the other person she may have punched or hit with the broom [found nearby]?'' she asked.
"If the investigation was done properly we may know about someone else there.''
Hair found in the victim's hands was not tested, she said.
The Crown linked the crime scene to what officers found in a wheelie bin outside the Merrit family's home on Nairn St two days after the incident - a hammer, glove and a hoodie covered in Ms Ross' blood.
Mr Bates said testing of the hoodie showed DNA from two sources, extremely likely to be the victim and Merritt.
The defence said the test was unreliable and the defendant's DNA could have been transferred to the garment from pizza boxes and drink bottles.
Blood in the Merritt house and a car was attributed by Mrs Stevens to the fact her client's mother Sharon Merritt was the one who found Ms Ross dead and rolled her over before calling emergency services.
The defence lawyer held her hand up to the recovered glove, telling the jury it was "like a child's''.
"A normal adult hand goes way over those fingers. Not one scientist, not one police officer bothered to measure Mr Merritt's hand. They had him at the police station for hours.''
Although the prosecution did not have to prove the defendant had a motive, Mr Bates said it was glaringly obvious.
"[Merritt] felt unfairly treated by Karin Ross,'' Mr Bates said.
Ms Ross and another colleague, Des Hurring, had filed a formal complaint about the defendant parking in a disabled spot and his behaviour; and Merritt had received a letter which said he might lose his job just hours before Ms Ross was attacked.
"She became the focus of his anger about the work situation,'' Mr Bates said.
He highlighted evidence given by Spotless employee Aiden Kelsall who remembered Merritt saying he would like to burn Ms Ross's family alive in front of her and that she deserved to die.
But Mrs Stevens said those comments were made weeks before the woman's death and came after she had publicly humiliated him.
When he received the disciplinary letters from Ms Ross, she said it was Mr Hurring who bore the brunt of Merritt's annoyance.
"So on the Crown's logic, Des Hurring should be dead. It was him he was angry with,'' Mrs Stevens said.
Mr Bates closed his comments to the jury saying: "I accept your task is a sad task, it's always an unpleasant task, but I suggest to you in this case it's not a difficult task.''
However, Mrs Stevens said the "bucket'' of Crown evidence had "one shot after another'' fired into it by the defence and no longer held any weight.
Justice Nicholas Davidson will sum up the case this morning before the jury of eight men and four women retire to consider their verdict.
