Authorities made a rare disclosure in the case Monday, releasing the names of four suspects in the shooting of U.S. Border Patrol Agent Brian Terry. A fifth suspect was arrested at the scene of the murder.

”Today the FBI seeks the public’s assistance in locating these dangerous fugitives. Today we stand in support of the Terry family and our partners in the border patrol.”

The killing took place during a controversial operation known as “Fast and Furious,” in which U.S. federal agents allowed guns to be smuggled into Mexico, hoping they would lead them to arms traffickers. But agents lost track of most of the weapons, two of which were used in the murder of Agent Terry.

The U.S. House of Representatives voted last month to hold U.S. Attorney General Eric Holder in contempt of Congress for refusing to turn over documents about the now defunct gun-running scheme.