House Speaker John Boehner wants to know, "Who's going to jail over this scandal?"

Speaker of the House Rep. John Boehner (R-OH) (Alex Wong/Getty Images)

He's talking about the Internal Revenue Service's targeting of conservative groups for extra scrutiny of their applications for tax-exempt status.

The Justice Department has opened a criminal investigation. And Attorney General Eric Holder will face questions about it this afternoon when he testifies to a House committee.

Holder has said he ordered the FBI to investigate on Friday -- the day the IRS acknowledged that it had singled out conservative groups.

Three congressional committees are already investigating the IRS for giving tea party and other conservative groups a tougher time with their applications.

A report released yesterday by the Treasury inspector general for tax administration said ineffective management at the IRS allowed agents to improperly target tea party groups for more than 18 months. It doesn't indicate that the practice was initiated in Washington. But it does say a top supervisor in Washington didn't adequately supervise agents in the field -- even after she learned they were acting improperly.

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