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BATON ROUGE, LA - JULY 17: Baton Rouge Police officers patrol Airline Hwy after 3 police officers were killed early this morning on July 17, 2016 in Baton Rouge, Louisiana. According to reports, one suspect has been killed while others are still being sought by police. (Photo by Sean Gardner/Getty Images)

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BATON ROUGE, LA - JULY 17: East Baton Rouge Police officers patrol Airline Hwy after 3 police officers were killed early this morning on July 17, 2016 in Baton Rouge, Louisiana. According to reports, one suspect has been killed while others are still being sought by police. (Photo by Sean Gardner/Getty Images)

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Authorities talk to the driver of a car near an area where several officers were shot while on duty less than a mile from police headquarters, Sunday, July 17, 2016, in Baton Rouge, La. (AP Photo/Mike Kunzelman)

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Ex-Marine who killed three officers in Baton Rouge served a tour in Iraq

He had filled prescriptions for anti-depressants and a sleep aid, source says

(CNN) —

Gavin Long, the man who killed three law enforcement officers in Baton Rouge, Louisiana, before a SWAT team officer shot him dead – told friends and relatives that he suffered from post-traumatic stress disorder, a source involved in the investigation told CNN’s Chris Cuomo.

Long joined the Marine Corps in 2005, worked as a data network specialist and served in Iraq before being discharged as a sergeant in 2010, according to the U.S. military.

Long had filled a prescription for Ativan, an anti-anxiety drug, as recently as June, said the source, who spoke on condition of anonymity. He also had prescriptions for Valium and the sleep aid Lunesta, the source said.

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