GATINEAU, Que. - "Capt. Rob boom, boom Taliban."

Those five words of broken English from an Afghan soldier led to second-degree murder charges against Capt. Robert Semrau, his court martial heard Friday.

Maj. Steve Nolan testified that a medic named Gulamjaan made the accusation about two months after Semrau allegedly executed a badly wounded insurgent on a battlefield in Helmand province.

The man was complaining: "Helmand, no good. Mission, no good. Taliban, no good."

Then he dropped the bombshell about "Capt. Rob."

Nolan said the words, accompanied by a shooting gesture toward the ground, prompted him to start asking questions about the October 2008 incident

Nolan said he went first to his sergeant-major.

"We started to talk about the possibilities of what this meant," he testified. "I came to the conclusion there was a very real possibility that a crime had been committed."

Nolan had the sergeant-major speak to a private who was on the battlefield at the time of the incident. He then spoke to his commanding officer, Col. Joseph Shipley.

"I told him that there was an allegation, or the possibility of an allegation from the Afghans ... they should probably investigate it."

Semrau was pulled out of the field shortly afterward by military police investigators.