Former New York State Assembly Speaker Sheldon Silver was indicted Thursday on three charges after his arrest last month in a federal bribery case. 

The indictment was returned in Manhattan federal court, where he appeared last month briefly when he was freed on bail just a day after sharing the stage with Gov. Andrew Cuomo during his State of the State address. The charges are honest services mail fraud, honest services wire fraud and extortion under the color of his official duties. 

"Our client is not guilty. We can now begin to fight for his total vindication. We intend to do that fighting where it should be done -- in court," Silver's lawyers, Joel Cohen and Steve Molo, said in a statement. Silver has said he is confident he will be vindicated. 

Silver's arrest came after he had led the Assembly for over 20 years, becoming one of the most powerful and savvy figures in New York state politics. 

But prosecutors said there was a dark side to his reputation as a potent backroom operator who played a major role in state budgets and laws, controlling which lawmakers sat on which committees and what bills got a vote. 

The government said he had collected nearly $4 million in bribes and kickbacks since 2002 and disguised the proceeds as legitimate income. 

The Democrat has since resigned as speaker but has said he intends to keep his Assembly seat. 

Silver's arrest rocked the state Capitol, even though state lawmakers' arrests have become ruefully common. Some 28 New York legislators have stepped down because of criminal or ethical issues in the past 15 years. Four others remain in office while they fight charges, including Silver. 

A day after announcing Silver's January arrest, U.S. Attorney Preet Bharara told a breakfast meeting at a law school that it sometimes seems as if Albany had become a "cauldron of corruption." 

He was particularly critical of what he called a "three-men-in-a-room" system of government that put too much control in the hands of the state's governor, Assembly speaker and Senate president.