The government’s explanation of how they found the Silk Road server is now being questioned by the attorney of alleged operator Ross Ulbricht, and follows a number of security researchers who also voiced their doubts regarding the FBI’s claims.

Ulbricht’s attorney, Joshua Dratel, released a statement Thursday saying that evidentiary fact finding, not unilateral government claims, is required. Dratel maintains that a hearing with testimony and cross-examination of expert witness is now “necessary to test the veracity and validity of the government’s assertions.”

“As the internet community has quickly recognized, the government’s facile explanation of how it located the Silk Road servers raises more questions than it provides answers,” said Dratel.

“Offering a selective narrative is easy, but without documented, forensic proof Special Agent Tarbell’s declaration simply does not suffice. As more and more commentators point out, the technical, logical and practical inconsistencies in this version require scrutiny in order to resolve the issue and arrive at the truth.”

One particular bit of information that might be useful for Dratel, and could add legitimacy to the FBI’s claims on how they found the server, is the packet log that led to this discovery.

Dratel previously questioned how exactly the FBI found the Silk Road server, which was hosted as a hidden service through the Tor anonymity software. If properly set up, Tor is designed to work to hide the location of servers hosted through it, yet the FBI somehow managed to discover the server location in Iceland.

The main concern of Ulbricht’s legal team was the legality of the FBI’s tactics to identify the server location; had they collaborated with the NSA in a possibly illegal “parallel construction” scenario? Theories arose questioning if the NSA had the ability to crack Tor itself.

But the FBI’s affidavit filed last week attempted to quell those concerns by claiming the FBI located the server due to a faulty CAPTCHA – not through NSA collaboration and not by cracking Tor. This claim only brought additional questions from security experts who say the explanation is not plausible for a number of reasons.

Security researcher Nik Cubrilovic said in a blog post on the subject, “Anybody with knowledge of Tor and hidden services would not be able to read that description and have a complete understanding of the process that the agents followed to do what they claim to have done. Were the Silk Road site still live today, and in the same state it was as in back in June 2013 when the agents probed the server, you wouldn’t be able to reproduce or recreate what the agents describe in the affidavit.”

Cubrilovic allegedly spent a good amount of time testing and investigating the Silk Road servers while they were still operational, and points out that Silk Road was likely one of the most scrutinized sites on the internet, due to its illegality and mass of bitcoins stored inside.

“The idea that the CAPTCHA was being served from a live IP is unreasonable,” continued Cubrilovic. “Were this the case, it would have been noticed not only by me – but the many other people who were also scrutinizing the Silk Road website.”

Cubrilovic even attempted to recreate the same exploit used by the FBI but couldn’t, and other secrutiy gurus pointed out that the FBI’s explanation just doesn’t add up.

Hence Dratel’s statement asking for additional hearings, evidence, and cross examinations.

“The government’s dismissive response to the concept of “parallel construction” is, of course, precisely what parallel construction is designed to achieve: a sanitized, opaque version of how information and evidence is obtained. It is a statement that resists further inquiry with categorical denial of access to information, other than that which the government decides to provide,” said Dratel.

“In that context, the government’s refusal to answer any of the questions posed in Mr. Ulbricht’s discovery motion is telling as well. A simple “no” in answer to questions regarding NSA involvement could end the controversy. The government’s failure to answer generates a presumption that either “no” would not be a candid response or the prosecutors do not know the answer.”