State prosecutors in the Manhattan district attorney’s office subpoenaed US President Donald Trump’s accounting firm for the previous eight years’ worth of personal and corporate tax returns in a bid to get to the bottom of the Stormy Daniels payoff case.

A Monday report by the New York Times noted that the documents are intended to settle the question of whether or not the firm that handles Trump’s finances, Mazars USA, falsified tax documents to conceal a hush payment to porn star Stormy Daniels by filing it as a legal expense, possibly violating New York state law. The subpoena seeks both state and federal returns.

Trump’s former lawyer, Michael Cohen, pleaded guilty last year to violating federal campaign finance laws for his role in the $130,000 hush payment, intended to ensure Trump’s alleged 2006 affair with Daniels remained concealed during the 2016 presidential election campaign. Cohen is now serving a three-year prison sentence for it.

Since Trump did not release his tax returns upon assuming the presidency - breaking a tradition dating back to Richard Nixon - courts and congressional committees have resorted to subpoenas seeking the documents to answer questions about the president’s past business affairs and their possible influence on Trump’s presidency.

The House Intelligence, Finance, and Ways and Means committees have all sought various financial records from Trump for different periods of time. However, prosecutors’ latest request seeks records from the previous eight years, going back to 2011.

Earlier this year, Albany lawmakers amended New York state laws to specifically permit US congressional committees to subpoena Trump’s financial records, Sputnik reported.

Last month, state prosecutors also subpoenaed documents from the Trump Organization itself for the investigation. The organization has complied with the requests, but other efforts to obtain Trump’s documents have seen repeated attempts at blockage by the president’s lawyers.