The police summary of facts said the pair had been in a relationship until they separated last year, but continued to live near each other in separate dwellings on the one property.
Waddel was allowed access to the main dwelling to wash his clothes.
Around lunchtime on June 9 this year, he went to a local pharmacy where he spoke with a shop assistant and sought more information on buying hair removal cream.
He told the assistant it was “for his wife who had sensitive skin”.
Waddel left the store with a tube of Veet hair removal cream, police said.
Last month, Waddel entered the premises where the woman lived while she was away, went into the bathroom, found her shampoo bottle and poured the hair removal cream into it.
The woman then began using the shampoo to wash her hair. She noticed it felt different on her scalp, and looked and smelled different.
She also noticed her scalp had become tender.
Police said the woman continued to use the shampoo, “thinking she was being paranoid”, but also noticed it would not lather as it should.
After trying once more, she rinsed the shampoo from her hair, realising that “something was indeed wrong with it”, police said.
The woman took the shampoo to her hairdresser. They compared it with the same labelled product and it was clear the contents were different.
By chance, the woman then found a receipt for Veet hair removal cream on the ground near a rubbish bin at home.
She contacted police and told them she suspected Waddel had added the cream to her bottle of conditioner as well.
She told police she had suffered some hair loss and that it possibly wasn’t the first time Waddel had laced her shampoo, as she had noticed changes in her hairline, which had begun receding in April.
Waddel admitted buying the cream and putting it in the woman’s shampoo bottle, in response to the way he perceived she had treated him, police said.
The charge carried a maximum of three years in prison.
Waddel was convicted of the charge and ordered to come up for sentence if called upon within the next nine months.
Tracy Neal is a Nelson-based Open Justice reporter at NZME. She was previously RNZ’s regional reporter in Nelson-Marlborough and has covered general news, including court and local government for the Nelson Mail.