Several news organizations have teamed up to ask a judge to force the United States government to reveal details regarding how it was able to unlock the iPhone of the perpetrator of the San Bernardino attacks in 2015, including how much it paid for third-party help in the process.

The Associated Press, Vice Media and Gannett—the parent company of USA Today—have filed suit against the FBI with the U.S. District Court in Washington in hopes of pushing the organization to comply with Freedom of Information Act requests.

The media groups aim to finally learn just how much the government paid to unlock the iPhone that belonged to one of the shooters who killed 14 people during the 2015 attack in San Bernardino, Calif.

Thus far, the FBI has remained as tight-lipped as possible regarding the information it has shared.  

After a public dispute with Apple in which the FBI attempted to push the company to unlock the mobile device for them, the agency turned to third-party sources to hack the iPhone and access its contents—including the attacker’s apparent communications with terrorist organizations.

In January, the FBI released more than 100 pages of documents regarding the hacked iPhone—done in response to legal pressure by the same news organizations—but the pages were heavily redacted and provided little context.

While the document shows that multiple contractors bid on the job, it does not disclose who won the bid or how much the FBI paid for its service.

The news organizations have argued there is “no adequate justification” for continuing to withhold the information and stated they have no interest in obtaining any information that would jeopardize national security.

“While it is undisputed that the vendor developed the iPhone access tool, the government has identified no rational reason why knowing the vendor's identity is linked in any way to the substance of the tool, much less how such knowledge would reveal any information about the tool's application," lawyers for the news organizations wrote in the filing.

"Release of this information goes to the very heart of the Freedom of Information Act's purpose, allowing the public to assess government activity - here, the decision to pay public funds to an outside entity in possession of a tool that can compromise the digital security of millions of Americans."

It is believed that Cellebrite, an Israeli security company, was tapped to break into the iPhone. Last month, nearly 900GB of data was stolen from the company and leaked online, including some details of what is believed to be the company’s hacking tools.