Government investigators in Washington state have dropped all charges against a man charged with child pornography offences, rather than reveal the technological means they used to locate him.
The case against Jay Michaud, for allegedly accessing and using the now-defunct Playpen site on the dark Web, was facilitated by FBI agents who used a Tor browser exploit to track him down.
The FBI took over the site and ran it for 13 days before they shut it down. A total of 135 people are now being prosecuted for allegedly accessing the website, according to a report at Ars Technica.
During those 13 days, the agency used an exploit that made it easy to identify from where people were accessing the site. The Tor browser allows individuals to browse the Web anonymously, masking both IP addresses and browser user agents.
{loadposition sam08}While the FBI calls the exploit a network investigative technique, others have described it as malware.
US attorney Annette Hayes said in a motion filed on Friday that as the government could not disclose the means that had been used to find out details of the people who accessed the Playpen site, the government had no option but to drop the action altogether.
In a related case in New York, the FBI has described the capabilities of the exploit it created.
Last year, the government was ordered by the court to hand over the source code for the exploit. But then the source code itself was classified, preventing defence lawyers from gaining access to find out how their clients had been traced.
Last year, there were reports that the Queensland Police Service's Taskforce Argos had hacked into the computers of Americans who were part of a child pornography ring on the dark Web, in order to find their IP addresses.
Argos is a specialist branch which investigates online child exploitation and abuse. The site in question was known as The Love Zone.
The QPS told iTWire at the time that Argos would not make any comment on the matter.