A former undercover US federal agent has pleaded guilty to extortion and related charges after acknowledging he channelled more than $US700,000 ($A915,810) in digital currency from the Silk Road online drug bazaar he was investigating.
In addition to extortion, Carl Force also pleaded guilty on Wednesday to money laundering and obstruction of justice.
The 46-year-old Force was tasked with masquerading as a drug dealer and establishing communications with Silk Road operator Ross Ulbricht, who was recently sentenced to life in prison.
After he infiltrated the website, Force sold Ulbricht information about the Silk Road investigation.
Force faces a maximum 20 years in prison when sentenced in October.
Former Secret Service agent Shaun Bridges earlier also agreed to plead guilty to theft charges stemming from his separate involvement in siphoning funds from Silk Road.
