The first tests for the Waikato family who were hospitalised after eating wild pig have come back negative for botulism.
Shibu Kochummen, his wife Subi Babu, and his mother Alekutty Daniel were hospitalised last month with suspected botulism after eating wild boar.
The trio reportedly still suffer severe after-effects, including heavily slurred speech, but are on the path to recovery.
Hospital notes for Mr Kochummen have been posted on YouTube by the TV Wild show, and state the first tests failed to find the deadly bacteria.
Further tests are now under way to find the cause of the mystery symptoms. Family friend Joji Varghese said doctors believe they might never know what caused it - but that this is unacceptable.
"That is not good enough especially when we know there are poisons being dropped that are controversial. If they cannot confirm botulism then they should at least be able to say what it is," he told TV Wild.
"Let them go through all the battery of tests and let them all come back negative and then we will accept the statement that we might have to live with not knowing, but not before those tests are done."
He had speculated in a Radio New Zealand interview that poison was to blame. He said the family has been tested for mercury, arsenic and lead poisoning.