A 21-year-old Dunedin cleaner killed his supervisor because he disliked her and she had complained about him, the Crown says.
Alexander Merritt has been charged with murdering 51-year-old Karin Ross, and his trial in the High Court in Dunedin began today.
Ms Ross was found dead early one morning in December last year in the Spotless Cleaning carpark on Strathallan Street, in Dunedin's harbourside industrial area.
Under questioning by Crown prosecutor Robin Bates, Mr Merritt's mother, Sharon Merritt, said her son lived with her, and she had originally got him the job at Spotless where she was a supervisor.
The Crown said Ms Merritt was first on the scene, finding Ms Ross dead at 2am.
Earlier, Crown prosecutor Richard Smith said, although the Crown did not have to prove a motive for murder, there was a clear one.
Mr Smith said Mr Merritt had formed a strong dislike of his supervisor over a number of months, and she had laid complaints about his behaviour.
The Crown's case is that the situation came to a head when the company launched disciplinary action against Mr Merritt.
It said Mr Merritt found out his supervisor had laid another complaint against him on the day before she was killed.
Mr Smith said Ms Ross was killed after a struggle in the company carpark and had tried to flee her attacker.
Blood found on her cleaning van, which was still running when she was found, and on Mr Merritt's car, matched very strongly with both of them, sometimes up to a million million times more likely than an average person, he said.
And the Crown said a blood-stained hammer and glove were found rolled into a top in a wheelie bin at the Merritts' house, and the blood matched strongly there too.
The Crown also planned to call a mobile phone technician with evidence Mr Merritt was not at home at 1.30am on the morning of Ms Ross' death.
'Surprising gaps' in Crown's evidence, defence says
In an initial reply, Mr Merritt's lawyer Anne Stevens said he did not murder Ms Ross and had spent the night at home. There was no robust evidence to prove otherwise, she said.
"The defence case is that the scientific evidence that the Crown places so much reliance on has inherent uncertainties.
"There are surprising gaps in that evidence, you will hear, and the defence will question and challenge much [of] this evidence."
Ms Stevens also said the threats Mr Merritt made against Ms Ross were heat-of-the-moment things that anyone might say, and the evidence against him did not stack up.
More than 30 witnesses are expected to be called in the two-week trial.