Meanwhile, the Afghan policewoman suspected of killing a US contractor at police headquarters in Kabul suffered from mental illness and was driven to suicidal despair by poverty, her children said.

The woman was identified by authorities as Narges Rezaeimomenabad, a 40-year-old grandmother and mother-of-three who moved from Iran 10 years ago and married an Afghan man.

Her son Sayed, 16, and daughter Fatima, 13, recalled Rezaeimomenabad's severe mood swings, and how at times she beat them. They said she was consistent in bemoaning poverty.