Around 8:40 a.m. Sunday morning, Gavin Eugene Long, 29, opened fire on police officers in Baton Rouge, killing three and wounding three more, one in critical condition. Since his heinous act, information about Long has come to light. Here's everything you need to know.

Long was honorably discharged from the Marines in 2010.

According to a military source contacted by CBS News, Long, whose last address was in Kansas City, Missouri, was honorably discharged from the Marines in 2010 with a final Marine rank of E-5 (Sergeant). His service record included duty assignments in Camp Pendleton, San Diego and Twentynine Palms. "Military records show he received several medals during his military career, including one for good conduct, and received an honorable discharge," reports CBS.

Long railed against police and "crackers" online.

On his various social media accounts, including his Twitter account "Convos With Cosmos," (under the pseudonym Cosmo Ausar Setepenra), Long posted racist and violence-promoting material. In his posts, he labeled the government an anti-black "hate group," called for exacting "Justice (Blood)" or "Revenue" for the oppression of blacks, and repeatedly ranted against "race soldiers," by which he apparently meant police officers, whom he portrayed as targeting blacks.

Here are just a few examples of his tweets on the "Cosmos" account over a span of just five days:

"Violence is not THE answer (its a answer) but at what point do you stand up so that your people dont become the Native Americans…EXTINCT?" he posted on July 13. "Have u ever seen white people march for the things they needed?" he posted on July 11. "'Yes The Govt is a hate Group, They Hate Black People' -- @MrJayMorrison," he reposted on July 10. "You cant talk (or protest) the devil into changing his ways, this has never been done and never will # 1. Exact Justice (Blood) or 2.Revenue," he posted July 9 following a post that read, "#WhitePrivilegeMeans not wanting to actually CHANGE the system of white supremacy, but u want Blacks to learn how to suffer with dignity."

He was a black separatist and promoter of Black Liberation Theology.

The Daily Caller's Chuck Ross provides several highlights from Long's YouTube page, including videos revealing that he was a former Nation of Islam member and that he promoted Black Liberation Theology, the neo-marxist, race-based theology of Rev. Jeremiah Wright, whose church President Obama attended for 20 years.

In one video, Long discusses the book he wrote "for my dark-skinned brothers," which apparently pushes the ideology of Black Liberation Theology. "If you look at all the rebels like Black Panthers, Huey P. Newton, Malcolm X…Elijah Muhammad, they was light-skinned. But we know how hard y’all got it," said Long.

At one point Long clarified that he is no longer affiliated with the Nation of Islam, saying, "Yeah, I also was a Nation of Islam member. Don’t affiliate me with it. Don’t affiliate me with anything."

The Dallas killer, Micah X. Johnson, was also a black nationalist, sympathasizing with the New Black Panther Party and other militant groups.

He called for "revolution."

"One hundred percent of revolutions, of victims fighting their oppressors, from victims fighting their bullies, 100% have been successful through fighting back through bloodshed," Long says in one video he posted on YouTube.

In other videos and posts, he criticized protesting as just "for the women," calling for action rather than "emotional" protests: "If I’m peaceful protesting…I know they would try to arrest me, and I would die right there because you’re not going to kidnap me. I know my rights, but I stand on my rights. That’s what separates me, that’s why they’re afraid of me,” he said in a video he filmed in Dallas.

In a July 14 video on Sterling, Long said, "If I would have been there with Alton — clap."

Several outlets have reported that Long was a member of the anti-government, sovereign citizens group called the New Freedom Group.

He carried out his attack on police on his birthday.

Long was born on July 17, 1987. He chose his birthday for the day to "Exact Revenge (Blood)," as he put it on his Twitter account.

The Los Angeles Times provides some details on the six officers he shot:

The slain officers included two from the Baton Rouge Police Department: [Montrell] Jackson, who had worked on the force for a decade, and Matthew Gerald, a white, 41-year-old officer who had been with the department for less than a year. East Baton Rouge Sheriff’s Deputy Brad Garafola, 45,was also killed. The father of four had been with the sheriff's office for 24 years.

The sheriff’s office said Deputies Nicholas Tullier, 41, and Bruce Simmons, 51, were wounded in the attack. Tullier was in critical condition, and Simmons has non-life-threatening injuries. The third injured officer has not been identified.