Police are to look again at whether payday lender Wonga should be subject to a criminal investigation after it sent fake legal letters to pressure customers in arrears into paying up.
City of London Police discussed the case a year ago but it was previously decided that it should be left to regulators so the 45,000 consumers affected would not be delayed in receiving their compensation.
But it said that now that the Financial Conduct Authority's investigations have concluded and a compensation agreement has been reached, it will "be reassessing whether a criminal investigation is now appropriate".
Earlier this week, Wonga said it had agreed with the regulator to pay £2.6 million in compensation for the letters it sent from non-existent law firms.
City of London Police said in a statement: "In March 2013 the Office of Fair Trading (OFT) met with the City of London Police to consider their (OFT's) investigation into Wonga and whether it should be referred to the National Policing Lead for Fraud.
"The interests of the consumer were at the forefront of these discussions and directed the decision that the most appropriate course of action was for the OFT to continue to investigate as regulator focusing on but not limited to the consumer credit act, legal services act, and unfair trading regulations.
"Now that the regulator's investigation has concluded and a compensation agreement has been reached with Wonga, the City of London Police will be reassessing whether a criminal investigation is now appropriate."
The Law Society has already stepped up pressure for a criminal investigation to be held into Wonga.
The society, which represents around 160,000 solicitors across England and Wales, said it has asked the Metropolitan Police to investigate Wonga and consider whether any offences, such as blackmail or those under the Solicitors Act, have been committed.
It has also called on City regulator the Financial Conduct Authority (FCA) to hand over copies of its investigation. The FCA confirmed it had been contacted by the society but declined to comment further.
Law Society chief executive Desmond Hudson said: "It seems that the intention behind Wonga's dishonest activity was to make customers believe that their outstanding debt had been passed to a genuine law firm.
"It looks like they also wanted customers to believe that court action undertaken by a genuine law firm would follow if the debt was not repaid."
The case, which consumer campaigners described as a "shocking new low" for the payday industry, saw Wonga add charges to some customers' accounts to cover administration fees for sending the letters, from fictitious firms Chainey, D'Amato & Shannon and Barker and Lowe Legal Recoveries.
The FCA could not impose a fine on Wonga for what it described as "unfair and misleading" debt collection practices, which happened between October 2008 and November 2010, because the failings were uncovered by a previous regulatory regime and it does not have powers to issue retrospective penalties.
Wonga has apologised "unreservedly" and said the "few" people who were directly involved with sending the letters are no longer in the business.
A spokesman for Wonga said earlier today that its focus is on compensating customers who received the "unacceptable" debt collection letters.
The Law Society said that, in its letter to the FCA, it has asked the regulator to provide copies of the fake legal letters and the regulator's investigation files.
The society said it is also asking the Solicitors Regulation Authority (SRA), which administers the register of solicitors, to investigate whether there is a case under the Solicitors Act or under the Legal Services Act, "with a view to prosecution if the investigation discloses sufficient evidence".
The SRA has declined to comment on what it plans to do about this.
The title of solicitor is covered by Section 21 of the Solicitors Act 1974, as well as misuse of "any description implying that (a person) is qualified or recognised by law as qualified to act as a solicitor".
Section 17(1)(a) of the Legal Services Act 2007 prohibits any person, who is not entitled under the Legal Services Act to carry on activities reserved for qualified lawyers, from wilfully pretending that they are so entitled. Reserved activities include the issuance of court process on behalf of another person.
A statement from the Metropolitan Police said: "We have received a letter and we are currently assessing the contents. We have made contact with the person who wrote the letter."