The latest letter was addressed to MP Doug Woolerton, the party's president in 2005 when Sir Robert made a cheque 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."
Doubtless the officer assigned to deal with Sir Bob's complaint, when it is lodged will be Commissioner Howard Broad, or one of his immediate subordinates. And we can all guess what the outcome of THAT enquiry will be!!