The Afghan policewoman who allegedly shot and killed a US civilian adviser near the Kabul police chief's compound appeared to be acting with premeditation and crossed three checkpoints to get inside the highly secure enclave, sources tell TOLOnews.

The suspect, identified by Afghan officials as Nargis, is a 33-year-old married woman originally from the Mir Bacha Kot district of Kabul province. She lives in Kabul city's working class neighborhood of Wazirabad, according to police sources.

Nargis had lived as a refugee in Iran and Pakistan, like millions of Afghans who went to either country to flee conflict. She has traces of the Iranian dialect of Farsi in her speech, a civilian source familiar with the investigation told TOLOnews on condition of anonymity.

Nargis graduated from the police academy in late 2008 and was among the pioneering groups of female Afghan police cadets.

She worked at the District 6 police station in Kabul city shortly after graduation but was most recently employed in the gender section of the Ministry of Interior. Her husband is a civilian employee at the Ministry of Interior.

She had recently returned from a government-sponsored trip to Egypt, where she split from the visiting Afghan contingent and went missing for two days, saying she was lost in the unfamiliar city. Her supervisors failed to mention this in their report of the trip, the civilian source told TOLOnews.

The compound where she attacked the US adviser is a highly secure enclave in the center of Kabul that houses the Kabul governor's office, the police chief's compound, various government offices and courthouses.

On the morning of the attack, Nargis apparently wanted to attend the graduation ceremony of a literacy course for Afghan police, the source told TOLOnews. The ceremony was apparently canceled, so Nargis attempted to enter the enclave by convincing the guards first that she wanted to see the police chief, then the governor. She was told both officials were out of office.

When the US adviser entered the enclave, Nargis asked a nearby guard to confirm if the person was a foreigner. Receiving an affirmative answer, she followed the foreigner to a shop inside the compound where he was apparently buying an Afghan police memento.

Nargis, dressed in her police uniform and armed with the gun issued by the Ministry of Interior, fired at the foreigner's torso at close range, according to the source familiar with the investigation.

It is unclear how Nargis was able to get past the three checkpoints, with her gun, to get to the adviser in the most secure part of the compound. All outside security personnel entering the enclave have to check their weapons at the entrance.

There are no initial indications of a possible collusion from security personnel at the enclave, although it is likely that the guards were lax in checking a female police officer.

Kabul Governor Abdul Jabar Taqwa told TOLOnews that Nargis had hidden the gun in her socks.

Nargis remains in Afghan custody and is under joint Afghan-US investigation. She hasn't told much to investigators and has been weeping intermittently, the source said.

Police have denied Nargis had any connections with the insurgency, saying she acted out of personal grievances. But it is not clear if Nargis had previous encounters with the slain US adviser.

Insider attacks involving Afghan security personnel attacking Isaf troops have risen dramatically over the past two years, with 2012 being the bloodiest yet. Nato officials have downplayed insurgent involvement in the attacks, attributing most of them to personal motives or cultural differences.

Nargis is the first female member of the Afghan security forces to be involved in such an attack, and is among the rare suspects to be apprehended. Most are killed during the attack.