Baton Rouge Gunman Was an Ex-Marine Who Was Angry Over Alton Sterling Shooting | Inside Edition

Baton Rouge Gunman Was an Ex-Marine Who Was Angry Over Alton Sterling Shooting

Police say Gavin Eugene Long drove from Kansas City, Mo. to Louisiana Sunday, where he killed three cops on his 29th birthday.

Gavin Eugene Long, the man police say murdered three Baton Rouge cops on Sunday, reportedly did so on his 29th birthday.

In the hours after the weekend's horrific killing of the police officers in the already tense Louisiana city, other details are emerging about Long.

Among them, is the anger he professed to feel in the wake of Alton Sterling's death at the hands of Baton Rouge police.

Long also had a stint with the United States Marine Corps. He was deployed to Iraq from June 2008 to January 2009, according to reports.

 A military source told CBS that Long was a sergeant at the time of his honorable discharge in 2010.

Read: 3 Arrested - Including 13-Year-Old Boy - in Alleged Plot to Kill Baton Rouge Police With Stolen Guns

Long received multiple medals while in the Marines, including one for good conduct, according to military records. 

Also revealed is the pseudonym Long used in much of his extensive social media, which included a blog, now defunct Twitter and Instagram accounts and a YouTube account.

On the YouTube account, where he called himself "Cosmo Setepenra," he appears to have posted a video the day of the Baton Rouge shooting. In the footage, he discusses police oppression and anti-police brutality protests.

In one YouTube video, Long referred to the shooting of five Dallas police officers by another black former armed services member as "justice."

On his blog, "Convos With Cosmo," Long refers to himself as a "freedom strategist, mental game coach, nutritionist, author and spiritual advisor."

Long's last listed address was in Kansas City, Missouri, where court records show a man matching his name filed for divorce from his wife in February 2011.

According to the Associated Press, the records don't indicate why the couple divorced. The petition indicates they had no children.

On Sunday, police say Long utilized his military training after he drove a rental car from Missouri to Louisiana, where he ambushed police in Baton Rouge less than a mile from the city's police headquarters. 

Read: 1 Suspect Dead After Multiple Cops Shot, 3 Fatally, in Baton Rouge

"His movements, his direction, his attention was on police officers," state police Col. Mike Edmonson told reporters Monday morning.  "[He] certainly was seeking out police officers."

Three officers were shot dead, three others were injured. Long was killed at the scene.

Among the victims was 45-year-old Brad Garafola, an East Baton Rouge Sheriff's deputy and father of four. 

The other officers killed were with the Baton Rouge Police Department. 

According to officials, one of them is Matthew Gerald, 41, a former Marine and Black Hawk Crew Chief from Denham Springs.

Also killed was Officer Montrell Jackson, a 32-year-old 10-year veteran of the force. The third BRPD officer shot dead was Matthew Gerald, who had been on the force for less than a year.

Watch: 15-Year-Old Son of Shooting Victim Alton Sterling Calls for Peaceful Protests