Property developer Glenn William Cooper has pleaded guilty in Manukau District Court to fraud charges involving $800,000 of property transactions.
Cooper, 39, faced court on Wednesday on five charges laid by the Serious Fraud Office of dishonestly using a document.
The SFO investigated five property transactions Cooper carried out with one family from July to September 2011.
The SFO says Cooper bought properties at mortgagee sale and then onsold these properties to investors who were under pressure to consolidate debt.
Cooper used false sale and purchase agreements, concealing his interest in the properties from the banks and investors, and misleading loan application forms.
Acting SFO chief executive Simon McArley said it was a case of preying on investors who needed budgeting advice.
"The investors were sold on a fantasy that purchasing these investment properties would successfully consolidate debt and solve their problems," Mr McArley said.
"Mr Cooper played on the affinity he had built with one family in particular. This has only added to their financial strife."
Cooper has been remanded on bail and will be sentenced on March 8.