Government MPs tried to highlight criticisms of Labour MP and former associate immigration minister Shane Jones when Audit Office officials answered questions on their report into the Bill Liu citizenship decision.
The investigation was into the 2008 decision to override advice from officials and grant citizenship to a Chinese businessman.
The Auditor-General found no evidence of corruption in his handling of the case but did criticise most of those involved in different aspects of the decision-making process.
At a finance and expenditure select committee hearing on Wednesday, Deputy Auditor-General Phillippa Smith responded to an assertion from National MP Maggie Barry that Mr Jones made many mistakes, including intimidating officials and making the decision too quickly.
"We think he made the decision without all the information. The department, we think, fell short both in assessing the risk and ... in providing the information, and the minister didn't ask for it."