A former Drug Enforcement Administration (DEA) agent tasked with helping taking down the Dark Web's most notorious criminal — the recently convicted owner of Silk Road, Ross Ulbricht — has pleaded guilty to siphoning more than $700,000 worth of bitcoin for personal use while he worked undercover on the case in 2013.

Carl M Force, 46, faces up to 20 years in jail after pleading guilty to charges of extortion, money laundering, and obstruction of justice in a federal court in San Francisco on Wednesday. Force's other alleged partner in crime, secret service agent Shaun W. Bridges, 32, has also reportedly struck a plea deal with prosecutors over his involvement in the theft in 2013.

"While investigating the Silk Road, former agent Carl Force crossed the line from enforcing the law to breaking it," Assistant Attorney General Leslie Caldwell said in a statement. "Seduced by the perceived anonymity of virtual currency and the Dark Web, Force used invented online personas and encrypted messaging to fraudulently obtain bitcoin worth hundreds of thousands of dollars from the government and investigative targets alike."

Force and Bridges were senior members of a multi-agency team based in Baltimore that was investigating Ulbricht's involvement in the Tor-encrypted racket, Silk Road — a $1.2 billion black market bazaar that was often described as the Amazon.com of illegal drugs. Both resigned from their positions after they themselves were placed under investigation.

A criminal complaint filed in March in the Northern District of California revealed the agents allegedly used their knowledge of the website's operations and their insider connections to those being investigated to each steal hundreds of thousands of dollars worth of bitcoin, the supposedly untraceable digital currency. Authorities, however, traced some $776,000 in illicit bitcoin transactions to Force's bank accounts, while Bridges was found to have transferred more than $820,000 in bitcoin to personal accounts.

Ulbricht, 31, was arrested in October 2013 following a near two-year investigation. He was found guilty of multiple charges, including conspiracy to distribute drugs, money laundering, and engaging in a continuing criminal enterprise, and sentenced to life in prison on May 29.

During Ulbricht's trial, prosecutors presented evidence he attempted to hire a contract killer to murder a Silk Road user he believed was trying to extort him. Five murder-for-hire charges against Ulbricht were filed and are currently pending in a Baltimore court.

There was no proof that anyone was actually killed or hurt as a result of these alleged hit attempts, but the New York district judge allowed evidence related to the crimes to be introduced after the prosecution framed it at the trial as proof that Ulbricht ran the site.

In one of those alleged attempted assassination attempts, Ulbricht contracted Force, who was operating under his government-sanctioned pseudonym, "Nob," to commission the murder of a vendor he suspected of stealing from Silk Road.

While Force was conducting the investigation as Nob, the complaint against him states, he was also allegedly running a parallel scam under the aliases "French maid" and "Death from Above," which he used to steal bitcoin sent to him as part of the ongoing investigation on Ulbricht.