The charge relates to the removal of his electronic monitoring bracelet before he went into hiding.
Mehrtens will be sentenced on the drugs charges in the High Court at Auckland on September 10.
Mr Whitehead said police discovered Mehrten's whereabouts at a small rural property near Katikati while making inquiries into Mr Voudouris' death.
A 51-year-old woman living at the property, who police allege was helping Mehrtens avoid arrest, has been charged with being an accessory after the fact.
She will appear in Tauranga District Court on October 15.
Mr Whitehead said Mehrtens was originally arrested in May 2010 as part of Operation Acacia, a police investigation into the manufacture and sale of methamphetamine.
Mehrtens was granted electronically monitored bail but he removed his bracelet and went into hiding in December that year.
He did not appear at his trial last December and was found guilty of the drugs charges in absentia in the High Court at Auckland.
The charges included conspiracy to deal methamphetamine, possession of methamphetamine for supply, and two charges each of manufacturing and selling the drug.
The investigation into Mr Voudouris' death continues and police remain interested in hearing from anyone with information relevant to the inquiry.