Police have confirmed they have re-opened an investigation into whether National MP Todd Barclay secretly recorded a staff member.
Assistant Commissioner (Investigations) Richard Chambers said police had assessed a range of information and comment in the public domain over the past week, and are now talking to people who may have relevant information.
Any new evidence will be "carefully considered" to determine what, if any impact it has on the outcome of the original investigation, Chambers said.
"This will be a thorough process with oversight from a senior detective. However at this stage we are unable to put a timeframe on how long it might take."
One issue police will likely look at are claims Barclay installed CCTV in his electorate office.
Police previously investigated for 10 months but found insufficient evidence. Barclay declined to be interviewed for that investigation.
English released the statement he made to police during the original investigation after Newsroom website published a text in which he told former Clutha-Southland electorate chair Stuart Davie of the conversation with Barclay, as well as a settlement paid to the electorate's former secretary Glenys Dickson.
After English's admission, Barclay held a short press conference and said English's police statement was accurate, and apologised for his earlier "misleading" statements.
The next day he announced he would not seek re-election as Clutha-Southland MP, but would stay on until September's election.
Police could also examine what pressure was exerted on Dickson to drop her complaint.
Opposition parties have accused English of a cover-up, saying he allowed Barclay to continue denying the allegations despite being told by Barclay that the recordings had been made.
English yesterday tried to draw a line under the Barclay controversy after a week of difficult interviews, repeatedly saying he had nothing further to add to a "normal" employment dispute.
But police re-opening the investigation will keep the controversy in the headlines.
Before Barclay became MP, Dickson worked for English, who held the Clutha-Southland seat for 18 years before becoming a list MP.
English's texts and statement were entirely redacted by police when they released documents to the Herald under the Official Information Act in March.
New Zealand First leader Winston Peters has said he is troubled by that decision by the police and their wider handling of the case.
Peters compared the police decision that there was insufficient evidence to carry out search warrants to the "teapot tape" saga, when police searched New Zealand Herald offices after a complaint by then Prime Minister John Key.