The founder and former CEO of Turing Pharmaceuticals, Martin Shkreli, invoked his Fifth Amendment right against compelled self-incrimination on Wednesday, and he won't comply with a subpoena for documents issued from a Senate panel investigating pharma drug pricing tactics.

The 32-year-old Shkreli was also subpoenaed to appear before a different panel, the US House Committee on Oversight and Government Reform, to testify about the price of a life-saving drug he increased by more than 5,000 percent.

Shkreli became the poster child for greed last year after he raised the price of Daraprim—used to treat parasitic infections—from $13.50 a pill to $750. A single pill once sold for $1. Now facing criminal charges that he allegedly defrauded investors, Shkreli has said he should have boosted prices for the drug even more.

Shkreli most likely won't cooperate with the US House committee's investigation, either. The panel is holding a hearing on drug prices on January 26. He probably will invoke the Fifth Amendment again. What he says at that committee hearing could be used against him in criminal proceedings.

Committee member Rep. Elijah Cummings (D-MD) said in a statement that he's "been trying for the better part of a year to get information from Martin Shkreli about his outrageous price increases, and he has obstructed our investigation at every turn."

Shkreli took to Twitter Wednesday and mocked the House subpoena: "House busy whining to healthcare reporters about me appearing for their chit chat next week. Haven't decided yet. Should I?"

Sen. Susan Collins (R-ME) said Shkreli's refusal to cooperate with the Senate Special Committee on Aging "could hinder our investigation."

Shkreli was charged last month with allegedly running a Ponzi-like scheme and defrauding two hedge funds he previously managed and another one of the pharmaceutical companies he founded, Retrophin. He has pleaded not guilty and was released on $5 million bail he posted with a $45 million E-trade account.