An Afghan police officer fatally shot an American contractor at Kabul police headquarters early on Monday, authorities said.
The killing occurred a day after five policemen were killed by their commander in Jawzjan province, in the north.
The incidents added to a number of insider attacks by Afghan soldiers and police officers -- or attackers dressed like them. More than 50 people have been killed in Afghanistan in similar attacks this year, which the Afghan government calls acts of terrorism.
Monday's incident marked the first such an attack involving a female suspect, said Hagen Messer, a spokesman for NATO's International Security Assistance Force.
Sediq Seddiqi, a spokesman for Afghan Interior Ministry, said the woman, around 40, has been a member of the police force for two years. She was arrested and was questioned, he said.
The victim was identified as Joseph Griffin, 49, of Mansfield, Georgia, according to DynCorp International, which describes itself as "a global government services provider in support of U.S. national security and foreign policy objectives, delivering support solutions for defense, diplomacy, and international development."
The civilian contractor for the security assistance force was working as an adviser to Afghan police, said Maj. Martyn Crighton, another ISAF spokesman. DynCorp said Griffin had been supporting the Afghan Ministry of Interior and Afghan National Police Development Program.
Griffin, a veteran of the U.S. military who had served in American-based law enforcement positions, had supported several of the company's global training and mentoring programs since November 2000. He began his most recent assignment in July 2011, DynCorp said.
"Joe spent his career helping people all over the world, most recently working to help the Afghan people secure a better future," said Steve Gaffney, chairman and chief executive of DynCorp International. "The loss of any team member is tragic, but to have this happen over the holidays makes it seem all the more unfair."
A woman who answered the phone at Griffin's home said she had no comment.