She was in the Air Force. He was a fellow service member on the base. And he said that if she told anyone what he'd done, he'd kill her.
"I wouldn't dare tell no one. I didn't think anybody was going to believe me anyway."
She drank instead. And smoked marijuana and snorted cocaine. She fell out of the military and bounced from job to job.
Twenty-nine years after the 1983 assault, Fredericks has landed at the Baltimore VA Medical Center, where she says she is finally getting the services she needs.
The 48-year-old New Yorker is one of the growing number of veterans receiving treatment for post-traumatic stress disorder after suffering what VA officials call military sexual trauma.
One in five women screened by the Department of Veterans Affairs reports having experienced severe sexual harassment, attempted assault or rape during military service. VA officials believe the number of unreported incidents makes the actual percentage of women who have suffered military sexual trauma — also known as MST — significantly higher.
While MST is not itself a diagnosis, VA officials say the experience can lead to post-traumatic stress disorder, an anxiety disorder that can cause flashbacks, fear and isolation.
As the number of women seeking help from the VA health system has grown — female patients nationwide doubled to more than 310,000 from 2000 to 2010 — so has the incidence of PTSD related to sexual harassment or attacks.
Dr. Patricia M. Hayes, the VA's national director of women's health, likens military sexual trauma to incest.
"In the military, you rely on people in your unit to save your life, to serve together, to defend our country against the enemy," she said. "If some serious event like a sexual assault occurs, you've been betrayed by your unit and by the people that you've lived with and served with.
"So there are additional burdens of trauma that can occur because it occurred while in the military. And because you can't escape, except by going AWOL, you're living it 24-7."
The VA has military sexual trauma coordinators at each of its medical sites, and the agency has funded and conducted research on effective treatments.
National veterans groups applaud those efforts and praise the work of VA caregivers. But some say getting the VA's benefits administration to approve coverage for treatment of PTSD related to sexual harassment or attacks remains a challenge.
Within the MST program, "the counselors are very good," said former Marine Capt. Anu Bhagwati, executive director of the Service Women's Action Network, an advocacy group based in New York. "The problem really becomes about access and availability."
Bhagwati says VA figures obtained by the network show that while 53 percent of PTSD claims for combat are approved for coverage, just 32 percent of PTSD claims for military sexual trauma are.
"So you only have a 1-in-3 shot of getting your claim approved if you've been assaulted or harassed," she said.
Her group has sued the Department of Veterans Affairs for information about claims and approvals. Representatives of the Veterans Benefits Administration, the arm of the VA that considers claims, did not respond to messages seeking comment.