According to a current senior U.S. official and a senior intelligence consultant who worked with Davis, the 36-year-old American is a former Blackwater contractor who was posted to Lahore as part of the CIA's Global Response Staff, or GRS, a unit of security and bodyguards assigned to war zones and troubled countries such as Afghanistan and Pakistan. Members of the GRS most often accompany CIA case officers, who meet with clandestine sources.
Davis and a group of fellow security officers lived in a safehouse in Lahore. The CIA keeps safehouses for security personnel in an effort to limit the ability for militants to track their movements, the intelligence contractor said.
On Jan. 27, Davis left the safehouse and conducted an "area familiarization route," according to the senior U.S. official. He drove through various Lahore neighborhoods for several hours. It was during his route, two U.S. officials say, that Davis stopped at an A.T.M. and possibly drew the attention of two Pakistani men on a motorcycle.
Davis has told the police in Lahore that the two men were attempting to rob him when he fired several rounds from his Glock handgun, hitting them both. The police report says that Davis claimed one of the men had a gun cocked at him. Davis fired multiple rounds from inside his car, killing one man in the street, while the second died later from his injuries.
Davis then called for help from several other CIA security officers who shared his Lahore safehouse, according to a U.S. official and the intelligence consultant. As they arrived near the intersection, they accidentally hit a Pakistani motorcyclist. The motorcyclist later died of his injuries. Davis' colleagues were unable to get to Davis before the police arrested him. They left the scene and returned to their safehouse.
Within hours, they had destroyed all government documents at the safehouse, abandoned it, and retreated to the U.S. consulate for safety. Both have since returned to the U.S., according to a senior U.S. official briefed on the case.
The Pakistani government is under significant public pressure to prosecute Davis. The incident has set off massive anti-American protests and calls for Davis to be executed for the murders.
"Our first fear is that the sentiment of the street in Pakistan is, 'Let's take him and hang him,'" said a current senior U.S. official.
Reporting by ABC News' Matthew Cole.