The FBI is emailing QuadrigaCX victims, confirming the federal agency is investigating the circumstances around the Canadian crypto exchange's collapse.

According to an email sent to multiple users of the exchange and shared with CoinDesk, Valerie Gauthier, a victim specialist with the FBI, has been reaching out to former users of the exchange to alert them of a new portal containing information about the case, confirming that the investigation continues.

"A criminal investigation can be a lengthy undertaking, and, for several reasons, we cannot tell you about its progress at its time," Gauthier wrote.

Victims can contact the FBI at quadrigavictims@fbi.gov, though "inquiries about the status of the case will not be addressed," she wrote.

The FBI has reportedly been investigating Quadriga since March 2019, and it announced in June it was looking for victims of the exchange. At the time, the agency included a questionnaire for individuals to fill out.

Multiple email recipients told CoinDesk they filled out the questionnaire last year, while at least one user who did not receive an email said they did not fill out the form.

The FBI is one of at least four national investigative agencies looking into Quadriga, along with the Royal Canadian Mounted Police. The other two agencies have not been publicly disclosed, though an Australian investigative agency appears to be one of the groups.

Separately, Roger Knox, the founder and operator of Swiss asset management firm Wintercap, formerly known as Silverton, pled guilty to securities fraud before a Boston judge on Monday.

Knox allegedly facilitated market manipulation schemes, including pump-and-dumps on microcap securities, acquiring some $164 million as a result.

Notably, the U.S. Securities and Exchange Commission (SEC) has alleged that Knox coordinated his scheme with Michael Gastauer, who controlled WB21, a payment processor that Quadriga claims (in a separate proceeding) holding some $9.2 million in Quadriga's funds. WB21 disputes this claim and says it only holds a nominal amount of Quadriga’s funds, and Gastauer and WB21 dispute the SEC’s allegations.