"Sometimes there is a certain look in their eye," he said.
Graner is one of 100 former service members hired nationally by the Department of Veterans Affairs as outreach specialists to help get Iraq and Afghanistan veterans into programs aimed at easing their transition back to civilian life.
They frequent job fairs, welcome-home events and other places where troops back from the wars might congregate and look for those struggling to adjust. The goal is to persuade them to visit one of 230-plus vet centers nationwide, which are operated by the VA to offer free services from job hunting assistance to marriage and mental health counseling.
Experts applaud the effort to actively search for veterans who may need help, even if some advocates say the program should be much bigger.
"Reaching out to these guys is really important because they will try and disappear. They try and handle it on their own. They try and run for cover. They don't know ... what the symptoms are and how it's affecting them," said Elizabeth Brett, an associate clinical professor of psychology at Yale University School of Medicine.
The VA says more than 340,000 Iraq and Afghanistan veterans have either received services from vet centers or at least been contacted by outreach efforts, including people like Graner. More than 1.8 million U.S. troops have been deployed since 2001, the Department of Defense said.
In the wider VA health care system that also includes hospitals, more than 400,000 Iraq and Afghanistan veterans were treated in the six years through fiscal 2008. Of those, almost 180,000 veterans had preliminary diagnoses of mental disorders and another 92,998 had a preliminary diagnosis of PTSD.
Graner says some of the vets he meets say they don't have any problems.
"I just tell everybody that I come in contact with 'At least go get a screening,'" Graner said. "They can sit there and say they are OK, they are fine, but in all actuality they are not."
Graner, 25, has been working for a little over a year with the Fort Lauderdale Vet Center and estimates he has contacted about 1,500 veterans of various wars.
"When you can help somebody it is very rewarding, whether you help them or a family member," Graner said.
One case: Graner met retired Marine Chief Warrant Officer John Crandall at a barbecue with an Army unit. The 37-year-old, who'd worked in counterintelligence, told Graner he had been unemployed for 14 months and couldn't find work. He suffered from PTSD and his marriage had collapsed.
A short time later, they met again at a welcome home ceremony and Graner steered Crandall to a job interview for a personal trainer position at a Fort Lauderdale gym. Crandall was hired.
"I meet Derek in one day and he's got me a job the next," said Crandall said. "He's a veteran. I'm a veteran. That's extremely important."
Today, Crandall says he is doing well. He is a lively storyteller and holds court during a catamaran ride with other veterans as he talks about his three tours in Iraq and earlier deployments in Bosnia and Kosovo. The camaraderie between Graner and Crandall is obvious. They sit side by side, laughing and talking like old friends.
"You speak a language that no civilian can understand," Graner says.
Alfonso Batres, head of counseling at the Department of Veterans Affairs, says that experience from the Vietnam War showed that veterans feel comfortable talking to other veterans. The government was criticized after that war for not doing enough to help returning soldiers, particularly those with mental ailments.
"They are trying to not make the same mistakes," said Janice Krupnick, clinical psychologist and professor of psychiatry at Georgetown University School of Medicine.
The current philosophy is to make contact with vets as soon as they return and the outreach specialists are part of that early intervention.
"Their job is to make an empathetic connection and then refer them to where they need to go," Batres said.
Initially, 50 positions were created across the country. As officials realized more veterans needed outreach, they doubled the number, but there are no immediate plans to increase the total.
Paul Rieckhoff, executive director of the advocacy group Iraq and Afghanistan Veterans of America, says more still needs to be done and the government should be hiring "thousands" of Iraq and Afghanistan vets.
"This is a small move," he said.
Another outreach specialist is former Army Sgt. Rafiq Raza from the Orlando Vet Center. He was an intelligence analyst. His job now includes speaking at local colleges, sending out mass mailings, striking up conversations with strangers and talking to big groups of returning soldiers. He says a major focus for him is helping vets overcome the stigma many associate with PTSD.
"All of us who go over come back with something. Some of us are going to have some issues," he said.
"When you are in the military they put that warrior ethos inside of you ... You think its going to be easy when you get out. For a lot of us its a whole new set of challenges."