Mark Warden answered my knock on his front door.

"Do you want to come in?" he asked as he restrained two very friendly dogs.

We made our way to his dining room table and sat down. The man looked tired, like maybe he had not slept. Tears periodically ran from the corners of his reddened eyes.

“Everything’s a blur. I'm just not in a good state of mind to even do this,” said Warden.

Who could blame him? Just yesterday Warden got confirmation that his only son, 29-year-old Nicholas Alan Warden was dead. He died from wounds in a battle against ISIS in northern Syria.

“I didn’t like him going to Syria, no," said the grieving father.

But traveling to Syria fit a pattern for most of Nicholas Warden's life. Mark says his son was pre-occupied with fighting terrorists since he was a boy. The trigger: the attacks of 9/11.

"He was only in middle school. I was thinking, 'he’s just a kid, but he did what he wanted to do, I guess,'” said Mark.

When he was old enough, Nicholas signed on with the US Army, served with the 101st Airborne which included two year-long stints in Afghanistan.

After the army, Nicholas became a volunteer fighter of sorts. He signed on with the French Foreign Legion to fight Boko Haram in Africa. Earlier this year, he traveled to Iraq to join Kurdish fighters trying to defeat ISIS in the civil war ravaged Syria.

According to a video released by YPG, a Kurdish paramilitary group, Nicholas died July 5th outside the city of Raqqa. His father showed us a brief autopsy report. The examiner guesses an anti-personnel landmine caused his wounds. A field hospital amputated six-inches of his right leg. The fatal wound appears to have been a large gash in his abdomen.

Mark Warden is trying to come to grips with the loss of his only son. Normally, he'd be busy with preparation for a funeral service, but he's been told bringing his son's body back home could take two to six weeks. Maybe longer.