"But I really believe that it's somebody that is familiar with the inside, or made themselves familiar with the inside of the building."
Cooper said an "unusual and weird" occurrence happened last weekend.
She declined to go into detail, other than saying she suspected unauthorised people made a "proposed attempt" to enter the Lion Place property.
"So we're hyper-vigilant," Cooper said.
"We're unnerved about being targeted and unnerved about even the way we have shipments brought into our building."
She said police had started a forensic investigation.
Cooper said investigators had found DNA and faecal matter linked to the alleged burglars.
Cooper, Coop, Curate and Trelise Cooper garments were stolen.
As samples, none of these garments had the care labels or washing instructions all clothes sold in New Zealand must have.
Some of the stolen clothes were already viewable on Cooper's lookbooks for her upcoming collections.
"I don't think I will ever get my garments back ... What occurred is definitely very organised."
Cooper said she'd probably been naive about crime in the past.
"I don't understand crime. It's a whole other language to me."
"The upside is that the community have been incredible. The love we've been shown, so much love and generosity."
Cooper said many people gave gifts and kind wishes to her and some of her roughly 100 staff.
"New Zealand's a great place, actually. But there's just an element that isn't."
When the Herald approached Police for comment on any developments in the case, a spokeswoman said: "We are following lines of enquiry but are not in a position to comment on specifics at this time.
"We wouldn't want to speculate on the motive of the offenders at this stage."
Police previously said anyone with information should call police on 105, quoting file number 201019/3913, or phone Crimestoppers anonymously on 0800 555 111.
In recent years, burglars and organised criminals have targeted fashion retailers and manufacturers in Cambodia, the UK and the USA.
In January, Canada experienced a wave of luxury coat robberies. Canadian broadcaster CBC said stolen jackets were sold through social media and word-of-mouth.
In December, America's National Retail Federation said over two-thirds of its surveyed members had noticed an increase in organised retail crime.
