Former U.S. Army reservist Micah Xavier Johnson posted an angry rant against white people on the Facebook page of a group called Black Panther Party Mississippi last Saturday, denouncing lynching and the brutalizing of black people.
Five days later, police said on Friday, the Afghan war veteran took part in a sniper-style ambush of police officers in Dallas, killing five and wounding seven others before dying in a police-initiated explosion.
"Why do so many whites (not all) enjoy killing and participating in the death of innocent beings," Johnson, 25, wrote on Saturday above a video of what appeared to be people participating in a whale-killing.
In the disjointed July 2 post, Johnson expressed anger over lynchings of black people and "our ancestors" being beaten, mutilated and killed.
"Then they all stand around and smile while their picture is taken with a hung, burned and brutalized black person," he wrote. "They even go to our homeland and shoot our endangered wildlife for sport."
On Johnson's own Facebook page, which was deactivated on Friday, a profile photo showed him with one arm raised and fist clenched in a Black Power salute. The page included images of a Black Power symbol and a red, black and green flag associated with the Black Liberation Army.
U.S. Homeland Security Secretary Jeh Johnson said at a news conference on Friday that it was unclear if Micah Johnson was a member of a black nationalist group.
Johnson served as a private first class in the U.S. Army Reserve from March 2009 to April 2015.
His deployment in Afghanistan from November 2013 to July 2014 earned Johnson a number of service medals, according to Army spokeswoman Jennifer Johnson.
Attempts to reach Johnson's relatives and friends on Friday were not successful. It was not clear if he was employed.
Dallas police said on Friday that a search of Johnson's home yielded bomb-making materials, ballistic vests, rifles, ammunition and a personal journal of combat tactics. Johnson had no criminal record, police said.
Public records indicated that he lived in Mesquite, a suburb of Dallas, and the Army also listed Mesquite as his place of residence.
The assault, the deadliest for law enforcement in the United States since the Sept. 11, 2001, attacks, took place on Thursday night during a protest over the fatal police shootings this week of two black men in Louisiana and Minnesota. Those deaths fanned public outrage over excessive use of force by police, especially against black men.
FBI investigators look over the crime scene in Dallas, Texas, U.S. July 8, 2016 following a Thursday night shooting incident that killed five police officers.
Dallas Police Chief David Brown said earlier on Friday that police had tried unsuccessfully to negotiate an end to an hours-long standoff before sending in a bomb-carrying robot that killed Johnson.
According to Brown, Johnson told police that "he was upset about the recent police shootings."
"The suspect said he was upset at white people. The suspect stated that he wanted to kill white people, especially white officers," Brown said.
Johnson's Facebook page included a photo of him with Professor Griff of the hip-hop group Public Enemy at what appeared to be a book-signing event.
"I will not sit back and let these people assassinate my character and tie me to the Dallas shootings," Griff said on Twitter on Friday, adding, "I DO NOT KNOW THE SHOOTER."
According to media reports, Johnson's sister Nicole posted on Facebook after he was identified by news outlets that "those that knew him know this wasn't like him." The message had been deleted from her page by Friday afternoon.
On Friday, three police cars and several television news trucks were parked near the large, two-story brick house of Johnson's family in Mesquite, Texas, a middle-class Dallas suburb.
Neighbor Kimberly Smith said her son went to high school with Johnson. "He was a nice kid. My son was surprised he would cause any problem."
Army Lieutenant Colonel Major Michael Waltz, a former special forces officer and White House aide, said in an interview with Reuters that a video of the attack indicated that Johnson was "not only trained, but well trained."
The video was taken by a person at the scene and widely circulated on social media.
Waltz said Johnson appeared to have received "close-quarters battle" training, which focuses on urban combat.