Postal poisonings, with tempting chocolates, became a popular crime in the mid-1930s.
With three cases before the courts, the judge in an attempted-murder trial warned there was a risk of further copy-cat poisonings.
The spate of crime exploded into public consciousness with the death of Margaret May Smith, aged 22, at the coalmining town of Blackball near the Grey River on the West Coast on September 24, 1934.
The second case was a lopsided love triangle in Hastings that landed in court in July 1935.
In Blackball, Ethel Bragg and Jean Clark, both aged about 20, received a box of chocolates through the mail, addressed to both of them, and containing a note signed "Jim".
Maggie Smith worked next door at Dumpleton's bakery in the town's main street and heard her friends were handing out chocolates.
Clark and Bragg opened the box, although it is not clear if they ate any of the sweet, deadly treats inside; Smith was said to have consumed a number of them.
She collapsed in pain while working a dough machine, was put on a bed at Mr Dumpleton's home and, within an hour, was dead.
Miner John Skikelthorp Page, 36, was charged with murder and two counts of attempted murder.
Evidence in the Greymouth Police Court indicated there had been around 41 chocolates in the box. There were 16 empty paper cups and of the 25 remaining chocolates, 15 had been tampered with.
Five had holes, according to a Government analyst. Ten had been bored underneath and contained strychnine crystals, with plugs of chocolate having been replaced in the holes.
Page had come to New Zealand in 1922. At the time of his alleged crime he was living in a hut near a mill at Atarau, about 6km up the Grey Valley from Blackball. For 15 months, he had been gold prospecting in the Moonlight Creek area northeast of Blackball on the slopes of the Paparoa Range.
In statements to the police, Page admitted knowing Smith, but said he didn't know Clark or Bragg. He denied knowledge of sending the chocolates and tried to implicate another man.
"I am not the principal party in this," he said, according to a Herald report of police evidence.
Page was sent for trial in the Supreme Court, but the jury found him insane and not fit to plead. Justice Northcroft committed him to Seacliff Mental Hospital in Otago in September 1935.
Arsenic contamination in Hawkes Bay
Alma Lorraine Keith, 19, of Hastings, received a packet of poisoned chocolates through the post in May 1935.
Two months later, Phyllis Leslie Tui Marshall, 18, was committed for trial after appearing in the Napier Police Court, where she pleaded not guilty to a charge of the attempted murder of Keith.
The chocolates were mailed to "Miss A. Keith" in a small, square parcel inside a bag wrapped in brown paper. Her mother Clare opened the package, which also bore a note saying, "Will write tonight and explain if I can. - J."
It appeared to be the handwriting of Jack William Masters, a farmhand with whom Alma Keith was friendly. But Masters would later deny both that it was his writing and that he had sent the chocolates.
Clare Keith didn't like the look of the chocolates, and when Masters and her daughter came home, Masters took the package to the police.
Masters had worked on Marshall's father's station at Tikokino, about 35km southwest of Hastings. He acknowledged in the Police Court, answering Marshall's lawyer, that he was "paying attention" to both Marshall and Keith. He wrote often to Marshall and she wrote him the kind of letter that indicated she expected to marry him, the lawyer said.
"I had no intention of marrying her," Masters replied.
In police evidence, Marshall was said to have told of a quarrel with Masters. She determined that if he would not have her, he would not have Alma Keith.
"When I sent the chocolates to Miss Keith I did not intend to kill her," Marshall said in her police statement. "I wanted to make her sick and give her a good fright.
"I knew from the amount of poison I put in it would not kill Miss Keith. It took quite a lot of poison to kill the cat. I think I put only about a quarter of the amount in the chocolates that I gave the cat."
A Government analyst found 10 chocolate creams in the bag. They appeared to have been broken and stuck back together. The cream inside had been sprinkled with a grey arsenic powder, and some was on the outside of the chocolates too.
One chocolate, which had more powder than the others, contained enough arsenic to kill.
In the Supreme Court, Marshall's defence tried to implicate Masters.
To the jury, Justice Reed said there was no dispute the package was posted by Marshall. But did she know what it contained, he asked.
She had initially admitted her guilt, until three days before the trial, then raised a startling defence, one supported by her relatives' evidence.
"What you will probably conclude is that the girl is exceedingly clever, perfectly self-possessed, and an excellent witness. Against her, you have Masters - obviously not in the same street as the girl in the matter of brains, and labouring under the fact he has suddenly been faced with a charge of being the perpetrator of a diabolical attempt to murder a girl, using another girl as a tool."
The jury found Marshall not guilty.
Strychnine in Blenheim chocolates
Before the verdict, Reed had told the jury it was an important case because of the Blackball postal poisoning case and a third, similar, matter in Blenheim.
With such publicity, there was a danger of neurotic people being tempted to follow the same course.
In August 1935, Alma Evelyn Rose confessed in the Blenheim Magistrate's Court to having dosed sweets with strychnine and posted them to herself. She couldn't explain why.
The Magistrate, T. E. Maunsell, said there had been a morbid yearning for sensationalism.
Rose was put on a 12-month good-behaviour bond on the charge of contravening postal regulations that required posted poisons to be packed in a special cover.