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INDIANAPOLIS, Ind. – The public is slowly learning new details about the Thousand Oaks gunman, 28-year-old Ian Long, who walked into a bar and murdered 12 innocent people.

Authorities said he was a Marine Corps veteran who served in Afghanistan. They said in April police were called to his home for reports of a disturbance, where a crisis team felt he may have been suffering from PTSD.

All of this information is coming to light as the FBI digs into the gunman’s past. It’s what they do for all mass shooting incidents. They support local and state law enforcement.

“We certainly want to provide all the resources that we can. Both from say evidence response team, to our crime lab, to our analytic resources,” Former FBI Agent Doug Kouns explained.

Former FBI Agent Doug Kouns said they’re trying to figure out as much as they can about the shooter and why they would commit such a horrible crime.

“They’ll scour every database that’s available to them. Both open and closed, so I believe the shooter was former military so they will be looking into military records. They will be looking into employment records, social media, open source intelligence, friends, family, everything,” Kouns said.

According to FBI data, the number of active shooter incidents has increased slightly.

In the years 2016 and 2017, there were 50 incidents, 221 people were killed, 722 wounded. Twenty were considered to be “mass killings.”

Congress defines a “mass killing” as murdering three or more people in a single incident

In 2014 and 2015, there 40 incidents, 92 killed, and 139 wounded. Twenty were also considered “mass killings.”

“Looking at the past is the only way to help predict the future,” Kouns said.

Kouns doesn’t have an easy answer on how to stop mass shootings, but hopefully when the FBI digs into a killer’s past it may prevent another mass shooting from happening.

“Perhaps it will give us a clue, give them a clue as for what to better look for. How to stop the next one if there was going to be a next one, if there is any type of indicators demographics that would point law enforcement in the right direction,” Kouns said.

Kouns said understanding the full picture of what happened may help prevent the tragedy, but sometimes people commit evil acts that can’t be explained.

Kouns now runs his own company called Veracity. He’s a former Special Agent and Supervisory Special Agent of the FBI. For more than 22 years he served the Bureau in the field and at FBI Headquarters while conducting or overseeing criminal, counter-terrorism and counter-intelligence investigations.

His company Veracity provides background checks and private investigations. For more information, click here.