Manhattan federal prosecutors have opened a new investigation front targeting Bitcoin exchanges by issuing subpoenas, claims a new report.

Wall Street Journal reports, citing people familiar with the matter, that the US authorities are looking for customer-transaction logs and materials or any other information related to solicitation of investors of the exchanges including Mt Gox.

The investigation, said to be in an early stage, involves examining any possible tie or link related to processed transactions between the exchanges and the online drug market Silk Road. However, there isn’t any word on which other Bitcoin businesses have received subpoenas.

One of the sources said that the prosecutors and Federal Bureau of Investigation agents hadn’t reached any conclusions as to whether the exchanges were connected with Silk Road.

The new focus of the investigation follows the charging of prominent Bitcoin entrepreneur Charlie Shrem over alleged ties in funneling cash to Silk Road. Shrem is accused of conspiring with Robert Faiella from Florida to sell more than $1 million in Bitcoin to the users of Silk Road despite knowing that the Bitcoin would be spent on illegal activities including drug trafficking.

Bitcoin has been long-rumored to be the only form of currency accepted in Silk Road, where people can anonymously buy everything from narcotics to forged passports.

Last year, the arrest of alleged Silk Road founder Ross Ulbricht in San Francisco, being charged with counts relating to drug trafficking, money laundering and computer hacking in the illicit online marketplace in exchange for Bitcoins. Following Ulbricht’s arrest, the government shut down the website.

It is also not clear if the investigation relates to subpoenas issued to exchanges and companies that deal with virtual currency, back in February. According to Reuters, those subpoenas from the US Attorney’s office, focused on “how they handled recent cyber attacks,” like the distributed denial of service attacks that forced at least 3 exchanges including Mt Gox to suspend withdrawals.