KABUL, Afghanistan — The United States military has reopened a criminal investigation into a series of at least 17 murders of civilians in 2012 and 2013 for which Afghan officials blamed an Army Special Forces team, a senior Western official here said on Monday.

A spokesman for the Army’s Criminal Investigation Command in Quantico, Va., Chris Grey, confirmed that a criminal investigation of the deaths was underway, although he did not say when the investigation had begun. The senior official, who spoke on condition of anonymity because he was not authorized to discuss the matter, said the investigation had been reopened in recent weeks.

“All death investigations conducted by U.S. Army Criminal Investigation Command Special Agents are conducted to a thoroughness standard, not necessarily to a timetable,” Mr. Grey said, in an emailed response to questions. “The investigation has yet to be finalized. During the case review process, information and leads were identified that demand further investigation.”

Afghan military investigators who carried out their own investigation on the orders of Hamid Karzai, the president at the time, had blamed interrogators who were part of a Special Forces A-Team based in the Nerkh district of Wardak Province, including an interpreter who was said to have dual Afghan-American citizenship and three American soldiers who worked with him.