Three other birds were thought to have DNA from the same dog but the samples had degraded so the results were inconclusive.
Complicating the matter was the presence of saliva from another dog, most likely Dog #01, on Kiwi #01.
An email from a senior DoC ranger to the laboratory stated the identity of both dogs involved in the attack would need to be "100 per cent confirmed" to be certain of a successful prosecution.
For that reason, and because of the cost of ongoing DNA tests, which had by then reached $6000, charges against the dog's owner were dropped.
Sue Reed-Thomas, DoC's Northland operations manager, said further DNA analysis was inconclusive so the dog or dogs responsible could not be positively identified.
Due to lack of evidence, the charges were withdrawn and the matter had not proceeded further. No verified kiwi deaths had occurred in the area since then.
Reed-Thomas said everyone related to the inquiry assisted DoC with its inquiries.
The emails obtained under the OIA, however, suggest tension between DoC and the dog owners, or the dog owners' employers.
The emails were heavily redacted before being released - in one place an entire page was blacked out - so the full train of events is unclear.
The correspondence shows that at one stage the owner offered to cover the cost of further dog DNA tests, but when DoC rangers arrived to take fresh saliva samples they were not allowed to take the samples themselves or even be be present while the samples were taken.
As a result DoC staff could not verify which dogs the saliva came from, and the second batch of samples could not be used to confirm the first.
A Massey University pathology report showed the dead kiwi were three females and two males, ranging in weight from 1.5 to 2.5kg. All but one had been in good condition prior to the attack.
The sixth kiwi was not submitted for examination because it was too badly decomposed.
The six deaths were the most in one spate since at least eight kiwi were killed by dogs in the Wharau Rd area near Kerikeri in 2015.
