Noone said he resigned on Tuesday after being on leave for a month - two days before Auckland Transport says it terminated his employment.
"I don't feel like the due process has been fair. It's been very personal and the issues don't relate to corruption or misuse of public money."
Noone played a part in approving millions of dollars worth of roading and infrastructure contracts at Rodney District Council and then Auckland Transport.
Auckland Transport is examining invoices and contracts back to 2010 and the Serious Fraud Office is watching the investigation.
Councillors from the former Rodney district said the investigation needed to look further back.
John Watson said: "The question is for how long and how much - and who, if anyone else - was involved. Roading contracts are big money, there's a lot of money at stake there."
Noone was a second-tier manager at Auckland Transport reporting directly to chief operating officer Greg Edmonds. His salary would probably have been over $100,000.
The house where Noone lived with his girlfriend Nick Hanvey was sold on Friday, and the new owners said Noone had moved to South Auckland. Noone owns property at Puhoi and a holiday home near Whangarei.
Auckland Transport said issues came to light after an internal review.