Officer Craig Shaw was murdered in the line of duty over four months ago. Now, WFAA has obtained a comprehensive report that details a troubled past and that fateful day.
Badge number 2049 is now emblazoned on every Lancaster police car in memory of Shaw.
"I don't think there was anything that could have prevented this other than this individual not having a weapon," said Chief Keith Humphrey, Lancaster Police Department.
That individual was David Brown, Jr., the son of Dallas Police Chief David Brown.
Four-and-a-half months after 27-year-old Brown shot Shaw in a Lancaster apartment complex, WFAA has obtained the sheriff's department's final investigation, which reveals Brown's state of mind in the hours leading up to the deadly shootout.
"He told [his girlfriend] that his father Dallas Police Chief David Brown, Sr. was against him and believed his grandmother along with everybody else hated him," the report read.
Investigators said Brown's girlfriend "told us that he had been smoking "WET" the day before... He told her he was hearing voices in his head. His behavior was psychotic, paranoid."
The two-inch thick report also chronicled Brown's brief stay at a psychiatric hospital in 2006. He was diagnosed with bipolar disorder, admitted smoking marijuana daily and thought God was talking to him. The report said Brown stopped taking his medication.
On June 20, he murdered a man at his complex. Police intercepted Brown fleeing and Shaw fired almost 30 rounds from his AR-15 rifle. However, Shaw was struck in the top of his head by a one of Brown's bullets. He died instantly.
Shaw's shots did hit Brown. He was struck multiple times in the back of the head, shoulders and thigh. An autopsy showed Brown had marijuana and PCP in his system.
Afterward, a review of Brown's cell phone revealed 11 unread text messages, including one from his girlfriend urging him to stop taking drugs.
"Please don't do that stuff babe," she wrote. "I love you and I don't wanna be away from you. But when you're on that I'm deathly afraid of you. I don't like that feeling."
Brown never saw that text. Two hours later, he was dead after taking two lives.
Right now, the two weapons Brown used are believed to have come from pawn shops.
Lancaster says its internal affairs investigation will be finished some time in December. Humphrey said he and his officers still visit Shaw's family on a weekly basis.