Eugene Robinson’s characterization of congressional efforts to exercise legitimate oversight powers as a “witch hunt” did a great disservice to that important facet of our system of government [“The GOP’s partisan witch hunt,” op-ed, June 21].

The fact that top officials in the Obama administration continue to refuse to come clean about the timing and scope of their knowledge about “Operation Fast and Furious” should be a matter of serious concern for all Americans. A federal law enforcement officer — Border Patrol Agent Brian A. Terry — lost his life as a result of that ill-conceived program, along with a number of innocent people in Mexico. The best way to ensure that these tragedies are not repeated is to hold all of those responsible for this fiasco fully accountable.

Mr. Robinson also wrongly concluded that the epidemic violence in Mexico is attributable to weapons from the United States.

If the availability of firearms from our country were the actual cause of the approximately 50,000 cartel-related murders in Mexico during the past six years, it would be reasonable to expect that murders in our country by gangs and other criminal organizations would be much higher than in Mexico, since such weapons are readily available here in far greater quantities. In reality, the number of those types of murders is far less in the United States than in Mexico, which means that the true cause of Mexico’s alarming murder rate lies elsewhere.

T.J. Bonner, Campo, Calif.

The writer was president of the American Federation of Government Employees’ National Border Patrol Council from 1989 to 2011.