The Afghan policewoman suspected of killing a US contractor in Kabul suffered from mental illness and had even attempted suicide due to poverty, her children have told the Reuters news agency.
"She was usually complaining about poverty. She was complaining to my father about our conditions. She was saying
that my father was poor," her 16-year-old son Sayid said in an interview on Thursday.
Police identified the woman as Nargis Rezaeimomenabad, a 40-year-old mother of four, and said she had worked with human rights department of the police for two years and had earlier been a refugee in Pakistan and Iran.
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The policewoman approached the adviser as he was walking in the heavily guarded police chief's compound in a bustling area of the capital. She then drew a pistol and shot him once, a senior police official told Reuters.
The woman, a member of the police's gender equality team, is in custody, officials said. Mohammad Daoud Amin, Kabul's deputy police chief, said an investigation is under way to determine whether the killing was intentional or accidental.
She could enter the compound armed because as a police officer she was licensed to carry a pistol, he said.
Mohammad Zahir, head of the police criminal investigation department, described the incident as an "insider attack", in which Afghan forces turn their weapons on US-led coalition troops they are supposed to be working with.
If confirmed to be such an attack, the shooting would be the first time that a female member of Afghanistan's security forces has turned her weapon on a member of NATO's International Security Assistance Force (ISAF) or a foreign contractor.
At least 62 international troops and advisers have been killed in 47 incidents by Afghan soldiers or police this year. NATO forces, due to mostly withdraw from the country by 2014, have speeded up efforts to train and advise Afghan military and police units before the pullout.
NATO says about 25 percent of the attacks are caused by Taliban infiltrators but the rest stem from personal animosities and cultural differences between Western troops and their Afghan allies.
Meanwhile, four Afghan policemen have been killed and two wounded in an attack assisted by an insider loyal to the Taliban, officials said.
Attackers stormed the police post at Trin Kot, a remote district in the southern province of Uruzgan, before dawn and killed the officers as they slept, police spokesman Farid Ahmad Aiel told AFP news agency.
Abdullah Hemat, a spokesman for the Uruzgan provincial administration, confirmed the incident and also blamed a Taliban infiltrator.