Former ACT MP David Garrett has formally resigned from Parliament.
Mr Garrett was formally confirmed as an independent MP earlier this week, but on Thursday issued a statement saying it was untenable for him to stay on.
Mr Garrett quit the ACT Party last week after disclosing in Parliament that he used a dead child's identity to obtain a false passport in 1984.
He has now informed the Speaker of the House that he will resign as an MP altogether, effective from midnight on Thursday.
Mr Garrett says he deeply regrets the damage his actions have caused the ACT Party. He says the decision to quit politics is his alone and has been made without duress or inducement.
ACT Party leader Rodney Hide says Mr Garrett made an outstanding contribution in his short time in Parliament by championing the three-strikes legislation.
Mr Garrett will be replaced by the next person on the ACT list, Dunedin lawyer Hillary Calvert.
Sad turn of events, says Roy
The deposed ACT Party deputy, Heather Roy, says the circumstances surrounding David Garrett's resignation are sad, but now she wants to focus on the party itself.
Mr Garrett was one of the MPs who recently threw his support behind Rodney Hide as leader, when Mrs Roy questioned his leadership.
However, Mrs Roy says she had nothing to do with Mr Garrett's downfall, and nor has anyone connected to her.
She told reporters on Thursday that in the end, it was up to Mr Garrett whether he stayed on as an MP.