The prisoner is believed to have infected three other people in Waikato, two of them children.
Since the news broke yesterday, much debate pivoted on ideas the man must have picked up Covid-19 either in prison, or after crossing the alert level border.
But this afternoon, health officials proposed another option - that he was infected after leaving prison in Auckland, and before arriving home - possibly by the person who drove him to the bail address.
Corrections staff are confident the prisoner did not have Covid-19 while in prison.
Beales also revealed the prisoner had received his first dose of the Covid-19 vaccine on the day of his release.
The prisoner remained within the boundary of the bail address until September, when he visited a car park about 250 metres away.
He then presented himself to police because his address had become unavailable and the court had revoked his bail and issued a warrant for his arrest.
The man was then in Police custody overnight, before being transported to Mt Eden Corrections Facility on September 17.
Beales confirmed five prisoners at Mt Eden who are considered as close contacts have returned negative day 3 test results. The trio will continue to be tested and will be managed in quarantine protocols.
Two prisoners initially refused to be tested. However one has now been tested.
Seven staff members are also self-isolating at home, six have tested negative, with one test result not yet available.
To prevent any possible outbreaks, all newly received prisoners are managed separately from longer serving prisoners for their first 14 days in custody and are tested on day five and 12 during alert level 3 and 4.