Murder accused Helen Milner asked a co-worker months before she allegedly fatally poisoned her husband whether rat poison could kill a person, a court heard today.

When she used to turn up at work with muffins, her workmates would joke: "I hope she hasn't put the rat poison in the muffins today. We thought the whole thing was a bit of a joke," said one workmate.

The murder trial of the 50-year-old office administrator began at the High Court in Christchurch yesterday.

The Crown alleges Milner was determined to kill off her second husband Phil Nisbet, 47, and cash in her $250,000 life insurance policy just weeks after a non-suicide clause expired.


She denies two charges of attempted murder and one of murder.

Former colleagues at Christchurch-based grounds maintenance firm GSL have told the court how she used to moan about her home life and belittle her husband.

The diabetic would also tell how she thought Mr Nisbet was trying to kill her, by putting extra sugar in her food and evening drinks.

GSL owner and general manager Desmond Cameron said Milner once asked him if Mitre 10 sold rat poison.

Operations manager Gavin Moffat also told the court how she asked him if the hardware chain sold rodenticides.

Since it came after a conversation about her fears that Mr Nisbet was trying to kill her, he asked why she wanted it.

"She just grinned and walked out the office," Mr Moffat said.

Milner also asked staff at GSL, which did weed spraying work, what chemicals were kept on-site.

She was told they were kept locked in a shed, the court heard.

Mr Moffat said staff had a joke about it.

"We thought it was the same as the rat poison thing," he said.

The Crown alleges that Milner plotted to kill her husband, buying drugs under false names, asking friends for views on poisoning methods, and even offering to pay $20,000 for a hit man to kill Mr Nisbet.

After two failed attempts to kill him, she succeeded on May 4, 2009, most probably by crushing up to 50 tablets of anti-histamine Phenergan into his food then smothering him with a pillow, the Crown alleges.

She then faked suicide notes, it is alleged, and even sent a text message from his phone or her own phone suggesting he had committed suicide.

Police originally ruled he had taken his own life.

However after a coroner raised doubts over the death, a homicide probe was launched and Milner was charged with murder.

The trial, before Justice David Gendall, continues.