The firm was also hired to investigate the risk of any spillage of pellets or 1080 dust from the helicopter operation transporting and storing the bait. It also looked into whether the operation was keeping the public safe.
The Ministry of Health will be releasing further information on this matter soon.
The Ministry of Health is one of a number of Government agencies that have used the Auckland-based company, which is at the centre of a probe by the State Services Commission.
The ministry has said it had a one–year contract with the company, capped at $70,000 excluding GST. The contract ended on June 30.
Last month it was confirmed that the director of private investigation firm Thompson and Clark bought psychoactive substances including synthetic cannabis on behalf of the Ministry of Health.
Thompson and Clark director Gavin Clark visited shops selling psychoactive substances to ensure they were complying with the Psychoactive Substances Act and "at times making controlled purchases of products such as synthetic cannabis".
The bulk of the work carried out by Thompson and Clark had been monitoring retailers to ensure they were complying with regulations restricting the sale and supply of high-powered laser pointers (HPLPs), the ministry said in a statement.
A spokesperson for the Ministry of Health said, last month, it supported the SSC's inquiry and continued to provide updates which might fall under the new broadened scope of the commission's inquiry.
"It's important to note that Thompson and Clark Investigations Limited is identified as an approved whole of government provider of services," the spokesperson said.