SAN FRANCISCO (Reuters) - A former U.S. federal agent was sentenced to 78 months in prison on Monday for stealing bitcoins during the government’s investigation of Silk Road and for secretly soliciting payment from the operator of the online black market for information on its probe.

A Bitcoin logo is displayed at the Bitcoin Center New York City in New York's financial district July 28, 2015. REUTERS/Brendan McDermid/Files

Carl Force, a former U.S. Drug Enforcement Administration agent, admitted to charges of extortion, money laundering and obstruction of justice. In a San Francisco federal court on Monday, U.S. District Judge Richard Seeborg said the scope of his betrayal was “breathtaking.”

U.S. prosecutors had requested an 87-month prison sentence, while Force’s attorneys asked for a four year sentence.

Force’s attorneys said he deserved less time partly because of mental health issues. In court on Monday, Force apologized to the American people, and to his family.

“I’m sorry, I lost it and I don’t understand a lot of it,” Force said.

Silk Road operated for more than two years until it was shut down in October 2013, generating more than $214 million in sales of drugs and other illicit goods using bitcoins, prosecutors said.

Ross Ulbricht, Silk Road’s creator who authorities say used the alias “Dread Pirate Roberts,” was sentenced to life in prison in May after a federal jury in Manhattan found him guilty of several charges, including distributing drugs through the Internet.

Prosecutors also reached a plea agreement with Shaun Bridges, a former Secret Service agent who was charged along with Force in March with stealing bitcoins, the web-based digital currency, during the investigation.

Force and Bridges belonged to a Baltimore-based federal task force that investigated Silk Road. Force played a prominent role, communicating with Ulbricht while posing as a drug dealer named “Nob,” prosecutors said.

According to a government document, Force, operating as “Nob,” in August 2013 convinced Ulbricht to pay him $50,000 in bitcoins by pretending he had information on the investigation.

While Force reported the discussion to the DEA, he falsely claimed no payment had been made but instead diverted the bitcoins to a personal account, prosecutors said.

Force, also without authorities’ knowledge, used another online moniker, “French Maid,” and offered Ulbricht information on the investigation for about $98,000 in bitcoins in September 2013, prosecutors said.