Edna Martin was driving her cousin through Seattle in late 1975 when she stepped out to run an errand, leaving him sitting in the car. When she returned, he was no longer inside. A crowd had gathered around him. With his arms outstretched, he spun in place, looked up at the sky and declared, "I’m Ted Bundy."

The law school student had been arrested a few months earlier in Utah and released on bail. By then, investigators were starting to connect him to a string of abductions and murders. Bundy bore an eerie resemblance to the suspect they had been looking for. The family refused to believe he was their guy.

Martin covered his mouth with her hand and rushed him back into the vehicle. They drove in silence. After a few minutes, she glanced over at him. He was smiling.

Martin’s heart sank. At that moment, she realized the accusations were true. Quietly, she panicked, wondering if she would need to crash the car if he suddenly lunged at her. When they arrived at his house, he stayed silent, calmly stepped out of the car and walked inside. Martin collapsed on her steering wheel and told herself, "He did it."

"My parents, my brother — we were just saying, ‘This can’t be. It has to be some kind of mistake. They caught the wrong guy,’" Martin, now 74, told Fox News Digital. "Maybe he was in the wrong place at the wrong time."

According to Martin, Bundy was five years older than she was. When his family moved to Washington, they lived under the same roof as hers for about a year.

"His mom had him out of wedlock," Martin explained. "In the mid-1940s, that was a harsh label to live with. People were hard on unwed mothers back then, and my parents wanted to give Louise, his mom, a second chance. So he was part of our family from the very beginning."

"He was always very nice to me," she said. "He always took time to talk to me. He seemed normal — outgoing — and my parents loved him."

Looking back, Martin said she witnessed moments of Bundy’s strange behavior that startled her — "as if he transformed in front of me." Around her friends, his jaw would suddenly clench, and he looked "mean." His bright blue eyes would turn black. When Martin called out to him, he’d shake his head and smile, as if nothing had happened.

For years, Martin wondered what had gone wrong with Bundy.

"I’ve often speculated about this, and maybe it was because of the times, but his mom would never tell him who his biological father was," she explained. "It became more and more of an urgency for him to know who he was. I don’t know if it’s because he was detecting things about himself or if he was just needing to know what that connection was on that side of the family."

"In 1969, he came through to see us on the way to Philadelphia so he could try to research and find out who his dad was," Martin continued. "I think that had a big effect on him. He never found out, and his mother withheld that information. Maybe she thought she was protecting him, but maybe it had another effect on him."

Still, Martin emphasized that whatever struggles Bundy faced could never justify the lives he destroyed.

From 1972 to 1974, female college students, like Martin, began to disappear, a light-colored Volkswagen Beetle driven by a man calling himself "Ted," he laughed it off as a case of mistaken identity.

Martin believed him.

"I remember when I was in Alaska and got a phone call that he’d been arrested," Martin said. "I just ran [until] I finally felt safe enough to scream it out of my system — because how could that be? Everything I thought I knew about someone was wrong. What it does — and you have to really fight this — is shake your ability to trust anyone. Now, when I look at people, I always wonder what’s behind the façade."

On Dec. 30, 1977, Bundy was being held at the Garfield County Jail in Colorado. He called Martin’s brother and asked which states had the toughest death-penalty laws. His cousin replied, "Most likely Texas or Florida."

GET REAL-TIME UPDATES DIRECTLY ON THE TRUE CRIME HUB

In January 1978, the FBI arrived at Martin's house. Bundy had escaped. According to the documentary, she wondered if he had "a death wish." Martin said she’ll never know the answer.

"He may have been drawn to the challenge of being somewhere that carried so much danger," she told Fox News Digital. "Maybe it was a place where getting caught could mean execution. You can’t help but wonder."

On Jan. 15, 1978, Bundy carried out a gruesome attack in Tallahassee, Florida, killing two Chi Omega sorority sisters and injuring three other women, The Associated Press reported. Less than a month later, he abducted, sexually assaulted and killed a 12-year-old girl named Kimberly Leach in Lake City, Florida, the outlet reported. She was Bundy’s final victim.

WATCH: TED BUNDY SURVIVOR SAYS LIGHT THROUGH BEDROOM WINDOW SAVED HER FROM SERIAL KILLER IN NEW BOOK

On Feb. 15, 1978, Bundy was arrested for the final time. In Florida, he was convicted of murder in 1979 and 1980. He was sentenced to death.

Martin said she wrote to Bundy repeatedly, hoping to understand what had driven him to kill. In her letters, she asked if there were other victims who’d never been identified and urged him to reveal where unrecovered remains might be. Bundy wrote back, but he did not provide her with any answers.

WATCH: TED BUNDY SURVIVORS REVEAL CHILLING PARALLELS BETWEEN BUNDY KILLINGS, IDAHO MURDERS IN FOX NATION SPECIAL

In 1989, Bundy was executed in Florida’s electric chair at age 42. For Martin, his death marked an end — but many questions remained.

Decades later, Martin said the experience permanently changed how she views trust.

"I did love that person," she said. "Is that hard to believe? I didn’t love the evil person. I really cared about the person I knew. All I could remember was the guy I knew. I didn’t know this other guy. … The trauma didn’t go away. And I found out you’re not supposed to bury trauma."