The Pensions Regulator has appointed an independent trustee for the 15 schemes linked to the now shuttered Fast Pensions.
Fast Pensions and five connected companies were wound up at the High Court in May.
According to an Insolvency Service statement, it is estimated around 520 people were persuaded to transfer a total of at least £21m of their pension savings into one of the 15 schemes.
Earlier this month, Dalriada Trustees was appointed as an independent trustee and will work the Insolvency Service on its investigation.
Investors were persuaded to transfer their pensions through various methods, including cold-calls that offered free reviews or questioned the performance of their funds.
Others, who were originally looking for credit, were advised by the companies connected to Fast Pensions that they could get a loan if they transferred their pension to one of Fast Pensions’ schemes.
However, the Insolvency Service says investors were not told information about returns or the high-risk and illiquid nature of the investments.
Investigators found that at least £4m was used to pay commissions and the remaining money was mostly used to make loans to companies that were connected with Fast Pensions.
The six companies liquidated were: Fast Pensions, FP Scheme Trustees, Blu Debt Management, Blu Financial Services, Blu Personal Finance, and Umbrella Loans.