(The Hill) — Rep. Darrell Issa (R-Calif.) issued a scathing reply to Attorney General Eric Holder over his role in the authorization of a botched gun-tracking operation and the Justice Department’s cooperation with a congressional investigation.

As chairman of the House Oversight and Government Reform Committee, Issa said the DOJ has tried to detract his panel’s investigation into Operation Fast and Furious since it began, offering “a roving set of ever-changing explanations to justify its involvement in this reckless and deadly program.”

In a letter sent to Holder on Sunday and publically released on Monday, Issa lists several instances in which the DOJ either denied the existence of the gun “walking” tactics used in Fast and Furious — the process of allowing for the sale or delivery of firearms into the hands of suspected criminals — or dragged its feet in turning over documents the committee had subpoenaed.

“All of these efforts were designed to circle the wagons around DOJ and its political appointees,” wrote Issa.