A probe into the escape of genetically engineered plants from a government laboratory found scientists had left routes open.
Scientists also washed out their high-security specialist containment laboratory with water that was flushed straight into the storm water system.
Details of a criminal investigation into a GE breach at a Plant and Food Research glasshouse laboratory are exposed in papers released under the Official Information Act.
The Ministry of Agriculture and Forestry documents describe a slew of failures and oversights by the government agencies charged with overseeing New Zealand GE laws.
The errors were made by the Environmental Risk and Management Authority, charged with allowing the importation and use of GE material; Plant and Food Research; and MAF, which audits the controls.
The investigation by MAF's enforcement unit was launched after GE cress plants (arabidopsis thaliana) were found growing outside a supposedly secure glasshouse.
The glasshouse was on Lincoln University property in Christchurch but leased out to Plant and Food Research for its experiments. A senior staff member followed protocols and alerted MAF after the cress leak.
In the six months that followed, scientists refused to be interviewed by MAF staff, potential evidence was destroyed and paperwork showed the GE seeds used to grow the plants should never have been allowed into New Zealand.
The investigation led to no criminal charges being filed - because investigators could not identify beyond reasonable doubt how the seeds escaped confinement to grow outside the glasshouse.
Problems included Plant and Food Research staff using mesh over an air vent and a storm water drain that had holes bigger than the seeds they were meant to stop.
The issues began with the entry to New Zealand of two batches of seeds used in the experiment. The seeds were inaccurately identified as not GE on import documents.
The lead investigator said technically it could mean the "seeds were never cleared ... to enter the country".
The MAF audit also discovered Plant and Food Research was signed off as having passed the audit and "we simply take the operators' word for it that the work has been done".
The lead investigator also revealed that Plant and Food Research was the agency used to test and store the GE material collected in the criminal investigation.
He said he could not fault Plant and Food Research during the investigation but "they may have a vested interest in not identifying or locating any further positive sampling".
He said any further legal action could be compromised because the "primary suspect" had tested and stored the "exhibits".
The investigation was further stymied by the destruction of possible evidence on the lab coats of scientists working in the glasshouse.
The search of the surrounding area was also not completed to the satisfaction of the lead investigator.
Other documents revealed that scientists and staff initially refused to be interviewed by MAF staff. They cited a section of the Hazardous Substances and New Organisms Act which grants the right to silence when cooperating could lead to incrimination.
They eventually agreed to be interviewed, although many had a Plant and Food Research lawyer present. Investigators had a search warrant prepared to enter the lab and seize evidence because of the resistance they faced.
It was Plant and Food Research's second major breach of GE containment in two years.
Sustainability Council executive director Simon Terry said a review of the nation's defences and controls on GE importation and testing was critical.
"The bottom line is that meaningful accountability for an escape was nowhere to be found."
Plant and Food Research ducked for cover when questions were raised over its handling of the GE cress seeds.
Communications manager Roger Bourne said no staff would be allowed to be interviewed and said, "We don't have to give a reason," before hanging up the phone.
Chief executive Peter Landon-Lane later rang and then also hung up.
An emailed statement from the company said it accepted MAF's findings and took the matter "seriously".