Veterans are about twice as likely as non-veterans to die by suicide. But the majority of those suicides are among veterans aged 55 or older -- whose military service was decades earlier.
Robert Neilson's military service ended decades ago. He was drafted in 1961 and spent two years in the Army just before the Vietnam War.
But that experience still weighed on him three years ago, when he sought help from the San Diego VA after contemplating suicide.
"That's what brought me into the emergency room," said Neilson, who's now 76.
It wasn't Neilson's first time seeking treatment. He said he also considered suicide shortly after getting out of the service. He remembers standing on a subway platform in New Jersey watching a speeding train.
"And I just figured if I just hold my hands in the air, I could just let it suck me in," Neilson said. "Somebody shouted, 'What are you doing?' And that snapped me out of the trance."
Neilson traces his mental health issues to the trauma of a sexual assault he suffered while in the military. Still, didn't seek help for fifty years.
"I just figured I'll struggle through life," he said.
Suicidal thoughts aren't always linked to combat
All sorts of service-related issues can lie dormant, only to crop up later in life, according to Ron Stark, the founder of Moving to Zero, a nonprofit group in San Diego.
Stark counsels fellow veterans who have contemplated suicide. More than a few are elderly.
Veterans struggling with suicidal thoughts aren't always wrestling with memories of combat. Although he was never in combat, Stark suffered from depression most of his life. He remembers sitting by the roadside with a pistol and contemplating pulling the trigger.
He said some older veterans suffer from mental health problems because they feel they didn't accomplish enough in the service.
"We have things about stolen valor. Nobody wants to misrepresent themselves," he said. "So I was Vietnam-era. I'm not a Vietnam veteran. I was in Desert Storm, but I wasn't in combat. We're always talking about what we're not quite."
The military also establishes life-long habits, both good and bad. A soldier strives to be someone people can rely on, especially in critical situations. So if you're not feeling 100 percent, service members might decide it's better to keep it to themselves, Stark said.
"You have a bad day at work and you can go home. You have a bad day on a submerged submarine, people die," Stark said.
Older veterans may face many risk factors
The VA National Suicide Data Report for 2005 to 2016, which came out in September, highlights the alarming rise in suicides among veterans age 18 to 34, who had the highest rate of suicide - 45 per 100,000 veterans. But those 55 and older still represent the largest number of suicides among veterans.
Part of the reason is that the veteran population in the U.S. tends to be older. For veterans aged 55 to 74, the rate of suicide is 26 per 100,000, while nationally, the suicide rate in the same age group is 17.4 per 100,000. The rate ticks up even higher for veterans over 85.
The Veterans Health Administration has focused on finding risk factors that could lead people to kill themselves, such as isolation, previous suicidal thoughts, and access to firearms. Older men are also more likely to reject treatment for mental health issues.
The problem is that the VA still doesn't know who will attempt suicide among the people who have those risk factors.
"We're not very far ahead in terms of understanding who's out there, who's really likely to take their lives in the next hours, days, months," said Colin Depp, a psychologist at San Diego VA who has researched suicide among older veterans.
The VA emphasizes getting potentially suicidal veterans in the door, where health-care workers can deploy a range of treatments, he said.
As part of his own treatment, Neilson - the vet who was 73 before he sought help at the VA - is now writing letters of encouragement to fellow veterans who are just beginning treatment, as part of a VA program.
Neilson pulled out one of the letters he has written and explained how he can help veterans he will never meet in person.
“I don’t know you but I have faith in you," he read. "You’re going to make it.”
This story was produced by the American Homefront Project, a public media collaboration that reports on American military life and veterans. Funding comes from the Corporation for Public Broadcasting.