OCEANSIDE - Just days before a Marine from Oceanside was scheduled to come home, he was gunned down with two fellow Marines in Afghanistan. Now, his father is seeking justice for his son’s death.

“He just loved being a Marine. He just loved the whole idea about it. Loved serving his country, doing right by other people, helping people,” says Greg Buckley Sr., of his son Marine Lance Cpl. Greg Buckley Jr. The 21-year-old was killed while working out in a gym by an aide to an Afghan police chief. The military calls it an insider attack. However, Buckley Sr. believes his son was executed in cold blood.

Buckley Sr. says his son was there to train Afghan security forces as part of NATO's planned withdrawal in 2014. But instead he was killed by a supposed ally.

Buckley Sr. believes the government should have done more to protect his son from Afghan trainees. Now, he is turning his anguish into action. He has spoken out on television networks, sent hundreds of letters to lawmakers and even created a Facebook page about his fallen son.

In addition to wanting the Afghan gunman involved in his son’s death prosecuted in the U.S., Buckley Sr. is also calling on the president to bring American troops home before the end of 2014.

For an extended interview with Buckley Sr., click on the video on the left or turn to channel 612 and select News 12 Extra.