Mr Williamson resigned his ministerial portfolios this month after it was revealed that he twice called Superintendent John Tims, the Counties Manukau district commander, in January about the prosecution of wealthy businessman Donghua Liu for domestic violence offences.
Prime Minister John Key said the MP for Pakuranga had "crossed the line", despite assuring him he did not intend to influence the prosecution.
A timeline of events released under the Official Information Act this morning shows that Mr Williamson's office was provided with a copy of the emails that police planned to release to the Herald, which had also been given to the Prime Minister's office under the 'no surprises' policy.
The note for the evening of April 29 states "Mr Williamson attempts to contact District Commander Tims".
A spokesman for Police National Headquarters said Mr Williamson sent a text message to Mr Tims asking him to call.
"Superintendent Tims did not call or respond to the text."
The emails released to the Herald on May 1 showed that Mr Williamson rang Mr Tims about the family violence allegations again Liu. Mr Tims referred the inquiry to his Auckland counterpart, Superintendent Mike Clement, on January 20.
A week later, Mr Williamson rang Mr Tims again, who again asked Auckland City to respond.
Mr Clement asked Inspector Gary Davey to follow up the request and "determine how we respond to MP Williamson".
"He [Mr Williamson] started by saying that in no way was he looking to interfere with the process," Mr Davey reported back to his superiors. "He just wanted to make sure somebody had reviewed the matter to ensure we were on solid ground as Mr Liu is investing a lot of money in New Zealand."
Mr Davey said he told Mr Williamson the criminal case was reviewed by the senior sergeant in charge of family violence cases, as well as the police prosecution team.
In the emails Mr Davey said he told the MP the police would carry on with the prosecution. "I also explained the wider responsibility of police to pursue these matters [redacted]. I told Mr Williamson that the best advice he can give Mr Liu is to have him seek good legal advice. The conversation was polite and professional on both sides and he appeared to be accepting of the police position. I will leave the matter there unless I hear otherwise."
Liu has since pleaded guilty to male assaults female and assault with intent to injure and will reappear in the Auckland District Court next month.
After his resignation, Mr Williamson said he made five or six calls to police each year on behalf of people who approached him.
In Mr Liu's case he said: "There was no intention to do anything about screwing the outcome, but just to work out the focus of it.
"When I hung up I literally did not see that that was anything other than what a member of parliament would normally do on behalf of somebody who had asked.
"However it has become clear that the police believe that it does cross a line, the Prime Minister thinks that it was inappropriate for me to have made the call."
He said he was told of the December incident by a friend of Liu and was told by Liu's interpreter there was confusion over the incident.
"I said I would find out from the police what the status of all this is and has it come to an end." Mr Williamson said he was not "friends" with Liu.
"It is pretty hard to have a friend that you cannot speak a word of their language and they of yours."
Mr Williamson also lobbied a ministerial colleague to grant citizenship to Liu against official advice and performed the ceremony himself in his electorate office.
He also lobbied another National minister to relax the criteria for rich immigrants under the investment rules, which Liu also wanted changed before he goes ahead with a proposed $70 million property development which has stalled for three years.
- By Jared Savage of the New Zealand Herald
