"Based on the findings of a criminal investigation," the marines and the corpsman "have been charged with offences including kidnapping, murder and conspiracy in connection with the death of an Iraqi civilian in Hamdania, Iraq," Marine Colonel Stewart Navarre told reporters.
The marines allegedly took the man from his house on April 26, shot him to death and then left a shovel by his body to make it appear that he was planting a roadside explosive.
"All marines are trained in the law of armed conflict and are expected to fully comply with it," said Mr Navarre.
"The Marine Corps takes allegations of wrongdoing by its members very seriously and is committed to thoroughly investigating such allegations.
“The Marine Corps also prides itself on holding its members accountable for its actions," he added.
Mr Navarre said the marines have kept key congressional members informed of developments, and will continue to keep the public and the US Congress informed "of significant steps in the legal and investigatory processes."
He added that while he could not discuss specifics of the case, he said it "is critical to remember that the accused are presumed innocent."
Cluster of allegations
The case is one of a cluster involving allegations of US troops killing
Iraqi civilians.
The Naval Criminal Investigative Service has also been investigating allegations that marines killed 24 Iraqi civilians November 19 at the town of Haditha.
In that incident, marines are alleged to have gone on a rampage after a roadside bombing, which killed one of their comrades.
They are alleged to have gone house to house shooting men, women and children.
Five men were reported to have been killed in a taxi near the scene of the bombing.
The marines initially reported that 15 civilians were killed in the road side bombing that killed the marine.
An investigation was opened only after Time magazine approached the Marine Corps with eyewitness accounts and a videotape that told a different story.
An army general recently concluded a separate investigation into the
Marines' handling of the civilian deaths. It is now in the hands of Lieutenant General Peter Chiarelli, the number-two US commander in Iraq.
On Monday, the US military announced that three US soldiers had been charged with murder and attempted murder in connection with the deaths of three male Iraqi detainees in military custody.
It said three Iraqi detainees died during an operation May 9 near Thar Thar Canal in Salaheddin province, but provided no other details about the circumstances surrounding their deaths.
The incidents have caused deep consternation among US lawmakers who have questioned whether the stress of the war is eroding discipline among troops.
US military officials insist the incidents are isolated and do not reflect the standards of conduct upheld by most of the approximately 130,000 troops in Iraq.