About 150 people have been interviewed in a spiked heathcare products probe, inquiry head Detective Inspector Peter Read of Christchurch said today.
Four products have been recalled after being deliberately contaminated with poisonous chemicals.
The police investigation is centred on a Christchurch pharmaceutical distribution centre, which has not been named.
"It's a process
of elimination -- we've started at the customer end and the manufacturing end and worked our way through to the distribution centre," Mr Read told NZPA.
"It's a methodical process we've got to go through."
Interviews would continue into next week, but suggestions of imminent arrests was "speculation".
The four products recalled are Clearasil Deep Pore Cleansing Toner, Blis K12 Throat Guard, Narium Nasal Spray and Summer's Eve Feminine Wash Intimate Cleansing Mist.
All four products were tampered with around the same time.
Mr Read said the affected Clearasil and Blis products recalled yesterday may have been stocked in pharmacies in the South Island, Wellington, the Hutt Valley, Kapiti Coast and Wairarapa.
Affected batches had not been sold in supermarkets, he said.
Fingerprinting was a large part of the investigation into catching the offender or offenders.
"We'll use all the forensic ammunition we've got on this one," he said.
A spokesman for CDC Pharmaceuticals Ltd, a Christchurch-based wholesale distributor of pharmaceuticals owned by a group of South Island pharmacies, said the company was "familiar with the products" and was working with the police and MedSafe in a bid to "resolve the situation".
He did not know if CDC was at the centre of the police investigation, but acknowledged it had a large share of the local pharmacy market.
The original contamination scare last month was sparked by the discovery of the chemicals phenol and chloroform in the Narium and Summer's Eve products .
Only chloroform was identified in the other two products.
Concerns about the Clearasil product were raised by a pharmacy which noticed irregularities with products when the chloroform evaporated, lowering the content of the container, and caused the label to peel.
People affected by the contamination have suffered irritation and discomfort but no one has been seriously injured.
- NZPA
