Sir Robert Jones has written again to New Zealand First, this time threatening to go the police if he gets another "evasive reply" about where his $25,000 donation went.
The latest letter was addressed to MP Doug Woolerton, the party's president in 2005 when Sir Robert made acheque out to the secret Spencer Trust believing it was going to party leader Winston Peters and the party.
It follows a letter to immediate past-president Dail Jones, who Sir Robert said had "hedged" and simply replied that he did not know.
"My sole concern is the money was used for party purposes, but getting a straight answer from New Zealand First is a recipe for disappointment," Sir Robert said. "If the money has not reached the party, it constitutes theft. If I receive another evasive reply then clearly it is a matter for the police."
Sir Robert said he had no reason to seek answers from the Spencer Trust - administered by Mr Peters' brother Wayne, a Whangarei lawyer - because he had "no connection" with it. He made the cheque out to NZ First and it was its duty to respond, he said.
Sir Robert said he would happily co-operate with the Serious Fraud Office, but had not yet been contacted.
The SFO is "assessing" a complaint about donations to NZ First made last week by Act leader Rodney Hide.
A former SFO investigator said he saw "no reason" SFO director Grant Liddell could not use the office's special "fishing expedition" powers to look at the Spencer Trust paper trail as part of the assessment. He said as long as Mr Liddell was satisfied there were "public interest considerations", he could issue a "directive notice" to produce documents believed to be relevant.
