Internal Revenue Service (IRS) contracting official Greg Roseman invoked his Fifth Amendment rights to remain silent on Wednesday. A House Oversight Committee report released yesterday alleged he helped funnel almost $500 million in contracts to his friend, Braulio Castillo, the chief executive of Strong Castle/Signet Computers.

“By inappropriately using a personal relationship and abusing a provision designed to help disadvantaged businesses, the IRS and Strong Castle have made a mockery of fair and open competition for government contracts,” said House Oversight Chairman Rep. Darrell Issa (R-CA). “Taxpayers deserve accountability and the Committee is troubled by this unacceptable behavior.”

The crony contracts were a boon to Strong Castle, says the report. In just six months, Strong Castle, which previously made just $250,000 in yearly revenues, bagged contracts that could be worth almost $500 million.

Castillo denies the Committee’s charges.

“We have never received any improper preferential treatment, and have competed fairly for every contract that we have received,” said Castillo in a statement.

The report chronicles scores of texts, emails, and witness testimony showing Roseman helped steer contracts to Strong Castle.

The Hill says a memo circulated by Democrats on the committee says Roseman has been “reassigned pending a review of the situation by a Treasury inspector general.”

In 2012, the Treasury Department gave Strong Castle an award for being a top small contractor.