U.S. counterterrorism officials told lawmakers Thursday that uncooperative or less-than-capable local law enforcement in Libya, Egypt and Tunisia is slowing the search for suspects in the death of the U.S. ambassador and three other Americans in Libya on Sept. 11.

Authorities in the region have not yet arrested many of the suspects the U.S. wants to question about the violent attack on the American compound in Benghazi on Sept. 11, according to two U.S. officials briefed on a private House Intelligence Committee hearing Thursday, where counterterrorism, intelligence and law enforcement chiefs disclosed the information to lawmakers.

The U.S. officials, who spoke on the condition of anonymity because they were not authorized to publicly disclose the information, said Egypt has arrested Egyptian Islamic Jihad member Muhammad Jamal Abu Ahmad for possible links to the attack, but key al-Qaida sympathizers remain free. They added that U.S. requests to go after the suspects unilaterally have also been rebuffed. The arrest was initially reported by The Wall Street Journal.