It's been an emotional two and a half weeks for Sheila and Edward Clark.
"My world is going to be radically changed," Sheila said.
"It's been tough, it's been tough," Edward said.
Their 28-year-old son, Dusty, was shot and killed by a Clinton County deputy sheriff two weeks ago. Dusty allegedly pulled a knife out when officers went to his home in Altona to arrest him for failing to appear in court for an ongoing traffic ticket.
"PTSD is what brought this all on, I think," Edward said.
The Clarks say their son was not a violent person, but a young man who struggled with post-traumatic stress disorder. He spent four years in the Marines. But in 2009 he was diagnosed with PTSD and was not allowed to re-enlist.
"His struggle to fit into this world and wanting to be still in the Marine Corps was just tough for him," Sheila said.
His parents say they noticed a dramatic change in his behavior. Dusty isolated himself, would go days without sleeping, thought people were after him and even walked 25 miles in the woods from his home in Altona to his mother's in Plattsburgh.
"I asked him, 'what are you doing for it? Are you getting help for it?' He said, 'I don't feel like I have anything wrong with me, mom,'" Sheila said.
Just a few weeks before the fatal encounter with police, Dusty Clark's father called the New York State Police to come check on his son. He told them he was acting strange.
"I told them, I think he needs to be medicated, and they tried, tried and tried again to get him to go to the hospital and get checked out," Edward said.
On Dec. 30, Dusty went to church with his mother like they did every Sunday. He served as an altar boy and was an active member of the church's fundraising efforts. After church, she gave him several hundred dollars to settle the traffic violations.
"He said, 'mom, I love you,'" Sheila said.
Coincidentally, that is the same day the sheriff's deputies arrived to arrest him.
"It is really just a perplexing condition that operates differently in everybody," said Carmen Chroback of Clinton County Mental Health Services.
Chroback says while some people who suffer from PTSD recognize the need for help, others have a tougher time.
"People have a hard time when it is really fresh or when it is when they are having an intrusive thought or intrusive memory, or reliving an emotional experience, it can feel very present, and when that subsides it can feel not as important and not worth paying attention to," Chroback said.
While we will never know why Dusty Clark grabbed a knife, Chroback says people with PTSD tend to respond differently if they feel threatened.
"There's not a lot of options in survival mode, you are just doing the best you can and it doesn't leave a lot of room for problem solving, it doesn't leave a lot of room for options, it doesn't leave room that something else may be available for you, you are just in survival mode," Chroback said.
The Clarks wanted to share their son's tragic story, hoping to raise awareness about PTSD. Despite years of trying to get their son into treatment he refused.
"I love my son, he had issues, I tried to help him," Edward said.
"Dusty kept everything to himself, we may not know everything he went through," Sheila said.
While their son may no longer be with them, both Sheila and Edward Clark are thankful their son is no longer battling the demons in his head.
The Clarks feel the sheriff's deputies may have used excessive force while dealing with their son, but feel the bigger issue here was the fact he suffered from PTSD. The Clinton County district attorney and State Police are reviewing the case to determine whether the use of deadly force was justified. A final decision is not expected for at least another month.