FRANKFURT, Germany — Three American soldiers were charged with murder Wednesday in the deaths of four Iraqis who were bound, blindfolded, shot in the head and dumped in a Baghdad canal last year.

Four other U.S. soldiers have already been charged with conspiracy in the deaths, which apparently came shortly after the Iraqis were captured in April 2007. The Iraqis were killed in retribution for casualties within the 1st Battalion, 18th Infantry Regiment, according to military prosecutors.

The Army said in a statement released Wednesday that Sgt. John E. Hatley, 40; Sgt. 1st Class Joseph P. Mayo, 27; and Sgt. Michael P. Leahy Jr., 26 — all formerly assigned to 1st Battalion, 18th Infantry Regiment — faced charges of premeditated murder, conspiracy to commit premeditated murder and obstruction of justice. Their hometowns were not disclosed.

The allegations facing the men related to "the deaths of several detainees who were captured as part of combat operations last year," the Army said earlier this year.

Two of the other soldiers accused in the case, Staff Sgt. Jess Cunningham and Sgt. Charles Quigley, appeared at an Article 32 hearing in August, but no decision whether they should be court-martialed has been taken. Defense lawyers argued at the hearing that they did not participate in the killings.

In hearings in late August, soldiers who were on the patrol said the four Iraqis, probably Sunnis, were taken into custody following a shootout with insurgents, and taken to the unit's operating base near Baghdad.

None of the soldiers said they saw Cunningham or Quigley discussing anything at the time. Some said they were asked by Hatley and Mayo if it would be all right if the detainees were executed.

Hatley and Leahy were also charged with one count each of premeditated murder and conspiracy to commit premeditated murder in a death near Baghdad in January 2007. Leahy was also charged with being an accessory after the fact, the statement said.

The Army did not provide details on that death.

The men are still assigned to their current unit — the 172nd Infantry Brigade — and will face an Article 32 hearing, which has not been scheduled yet, said Lt. Col. Eric Bloom, a spokesman for the Joint Multinational Training Command in Grafenwoeher, Germany.

An Article 32 hearing is equivalent to a civilian preliminary hearing to determine whether there is sufficient evidence for a court-martial.

Spc. Belmor Ramos, 23, and Spc. Steven Ribordy, 25 — also of the 172nd Infantry Brigade — were charged with conspiracy to commit premeditated murder last week. Ribordy was also charged with being an accessory after the fact.

Ramos' court-martial appearance is scheduled for Thursday. A date for Ribordy's court-martial has not been set.