That amounts to about half of all U.S. aid to Honduras for 2012, including humanitarian assistance.
"This is one of a number of killings involving members of Honduran security forces that Senator (Patrick) Leahy is asking the State Department about," David Carle, a top aide to Leahy, said in an email.
Leahy, a Vermont Democrat who is chairman of the Senate's State, Foreign Operations and Related Programs Appropriations Subcommittee, has put a hold on some of the U.S. aid for Honduran military and police forces until his questions are answered.
Three soldiers have been charged in the case, one for murder. It is a violation of Honduran law to shoot at people who do not pose a threat.
The U.S. sent the leader of the squad, Josue Sierra, to cadet leader training last year at the Western Hemisphere Institute for Security Cooperation, formerly the School of the Americas, a Defense Department institute at Fort Benning, Georgia. Sierra was allegedly the first to fire at Yanes, according to court reports, and was in charge of the truck. He has been charged with attempting to cover up a crime and violating official duties.
Lt. Col. Reynel Funes, who allegedly ordered the soldiers to cover up evidence by swapping out their weapons at the armory, attended the Naval Postgraduate School in Monterey, California, in 2006 and the then-School of the Americas in 1984. Funes was being interrogated by prosecutors this week, along with two top military colonels, Juan Giron Reyes and Jesus Marmol Yanes. None have been charged.
In addition to withholding money from Honduras, the U.S. military has stopped sharing radar information with the Honduran air force after learning that suspected drug flights were being shot down.
Honduran historian Rodolfo Pastor said the responsibility lies at the highest levels.
"For years we have been saying Honduran soldiers and policemen are murderers," he said. "In the end, it is their officers and the highest civilian officials who have ordered murder and justified covering them up who are truly responsible."
Associated Press writer Alberto Arce reported this story in Tegucigalpa and Martha Mendoza reported from Santa Cruz, California.