WASHINGTON (AP) — The former head of the Internal Revenue Service heads to Capitol Hill on Tuesday, giving lawmakers their first opportunity to question the man who ran the agency when agents were improperly targeting tea party groups.

Lawmakers want to know what former IRS Commissioner Douglas Shulman knew and when he knew it. They also want to know why Shulman didn't tell Congress that agents had been singling out conservative political groups for additional scrutiny when they applied for tax-exempt status — even after he was briefed.

Shulman is testifying before the Senate Finance Committee, which has launched a bipartisan investigation into the matter.

ALAN FRAM,Associated Press

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