As facts continue to emerge about a botched gun investigation of Mexican cartels, U.S. Attorney General Eric Holder has given the American people reason to doubt his ability to effectively lead the Department of Justice.

His reasoning and judgment will be tested once again Thursday as he testifies about the “Fast and Furious” operation before the House Judiciary Committee.

Nearly a year after a U.S. Border Patrol agent was killed by a weapon linked to the botched operation, Holder’s Justice Department has spent far more time and resources trying to salvage the careers of senior officials who knew about the operation than in creating accountability for this tragedy and ensuring that nothing like this will happen again.

Conceived by the Phoenix Field Division of the Bureau of Alcohol, Tobacco, Firearms, and Explosives — a Justice Department agency — Fast and Furious began in November 2009 after calls by Justice officials to focus resources on Mexican drug cartel leaders rather than low-level straw buyers. At its core, the operation was intended to allow straw buyers to supply drug cartels with firearms in the hope that ATF could identify cartel members after the guns recovered at crime scenes in Mexico were traced to their original place of purchase.

This program, which Holder has finally acknowledged was “fundamentally flawed,” occurred with the knowledge and approval of Justice. Tragically, however, the program’s guns have been linked to numerous murders in Mexico. The operation was only halted after the death of U.S. Border Patrol agent Brian Terry a year ago in the Arizona desert. The two guns recovered at the murder scene both traced back to Fast and Furious.

To this day, the attorney general has disclaimed responsibility for the program that his department authorized and supervised. Specifically, Holder claims that he did not know about Fast and Furious until a few weeks before his May 3, 2011, testimony before Congress. Yet, he was sent numerous memoranda listing Fast and Furious as a significant investigation. Now it is becoming clear that even though Holder’s senior managers were fully aware of this program, they failed to end it:

•On March 12, 2010, then-acting Deputy Attorney General Gary Grindler received a detailed briefing on Fast and Furious. His handwritten notes show that the briefing included details on tactics and the fact that named individuals were buying hundreds of weapons for Mexican cartels. Since then, he has become Holder’s chief of staff.

•On Oct. 31 of this year, Lanny Breuer, assistant attorney general in charge of the Criminal Division, apologized for failing to “draw a connection between the unacceptable tactics” used in Fast and Furious and another program that employed similar tactics. He has retained his job.

•Last week, Assistant Attorney General Ronald Weich took the extraordinarily rare step of withdrawing a letter he sent to Congress because it contained false information. He has retained his job.

In the view of former acting ATF director Ken Melson, the department has been trying to manage its response in a way designed to protect its political appointees. That appears to be true.

Surprisingly, no one at Justice Department headquarters has faced any meaningful consequences. While replacing the entire ATF leadership structure and causing the U.S. attorney for Arizona to tender his resignation, Holder has consistently used a concurrent investigation by the inspector general to prevent him from acting against senior officials close to him.

Under such flawed and weak leadership at Justice, the American public has little reason to be confident that the next flawed program will be stopped before it, too, costs lives.

The president says he still has faith in the attorney general. If Holder, however, cannot foster a culture of accountability within his own department, President Obama would be wise to reassess the public interest.

Rep. Darrell Issa, R-Calif., is chairman of the House Committee on Oversight and Government Reform.