Bound by Friendship, Murder and Mental Illness

May 2, 2002 -- Charlotte Corash and Kathleen Hagen became instant friends in 1982, when Corash was a high school teacher and single mom, and Hagen was a divorced physician.

They met through a mutual friend, and realized they had a lot in common, including a love for skiing, boating, snorkeling, traveling, and having a good time.

In a friendship spanning more than two decades, their extraordinary bond survived — and flourished — despite dark secrets and unspeakable horrors. Not even a murder charge could break the friends apart.

On the Fast Track

Hagen was an only child who grew up in Chatham, N.J. Her parents doted on her, but demanded excellence. She went to Harvard Medical School, and from there, she was the first female urology resident at Massachusetts General Hospital.

"She was smart and she was a very meticulous surgeon," said Dr. George Prout, then the chief of the department. But he also said there were moments he saw another side to her. "There's no question that Kathy did have sometimes what we call a short fuse."

After a short stint at New York's Memorial Sloan Kettering Hospital, Hagen was appointed as the first female to chair the department of urology at Rutgers University Medical School in 1982.

The following year, Hagen met Bill Tyrrell, an engineer, at the Jersey shore. They married eight months later.

"I was ecstatic for Kathy," said Corash, who was divorced at the time. "I felt he was a good partner for her … Both extremely bright, intelligent, driven, focused people."

But the happiness Kathy was finding at home came at a time when her career was starting to slip.

"She liked fixing people, making people better, and I think she found that the paperwork was getting in the way," said Corash. "She wasn't smiling anymore. It was as if it started to become a chore."

Tyrrell, too, watched her professional life prove to be a struggle. "She complained about not being able to get things to go the way she wanted them," he said.

Five years after taking what seemed like her dream job, Hagen suddenly resigned.

Corash had no idea what was going on inside her friend's mind. Tyrrell, who knew the truth, wanted to put the best face on it.

"My reaction was, that if she was that unhappy with it, then, fine. We'll do something else," he said.

A Turning Point

The couple moved to their vacation home on St. Thomas in the Virgin Islands. Tropical fairytale gave way to the round-the-clock grind when they took over a small inn. In 1989, Hurricane Hugo came roaring through and all but crushed their paradise.

"She was frustrated, she was depressed, she was talking a mile a minute on the phone, screaming and yelling … she was out of control," said Corash.

Three years later, the couple came back New Jersey, living just down the street from Corash and her new husband. While Bill went back to his old job, his wife's life seemed aimless. And though the women loved being back together, Corash was certain something was very wrong with her friend.

"She was spending more and more time alone," said Corash, who also pointed out that Hagen was obsessively clipping coupons and hoarding flower pots.

There was a turning point in Hagen's marriage when Tyrrell got in a motorcycle accident in 1995.

"Kathy was at home," remembered Tyrrell. "She had been out grocery shopping when this occurred and was very concerned about getting home and putting the frozen groceries away … I was appalled."

Tyrrell's leg was mangled, and he made a decision to have it amputated. "She was very upset about it, screamed and yelled and carried on," he said of his wife's reaction. "[She] felt it was a thing being done without her good advice."

Corash watched her friend spiral out of control. "Kathy had become severely depressed to the point of psychosis. She had been hearing voices," said Corash. "She lost it. She went mad."

A Dark Secret

This was the dark secret Corash finally learned about her friend. For most of her life, Hagen — the brilliant, over-achieving physician — had been hiding an illness that ran in her family. She had been hospitalized twice for depression: once during her residency and again just before leaving her high-profile job at Rutgers.

Five years ago, Hagen and Tyrrell divorced, and Hagen moved back home to care for her aging parents.

As for her own life, said Hagen, "Unfortunately, I started to believe that I was unfixable."

Three years later, by the summer of 2000, she had stopped bathing. She didn't eat or sleep. She was unable to care for herself, let alone her father, who was 86, and her mother who was 92.

"It would take me four hours to get my shoes on. It would take me four hours to go grocery shopping where I might have done it in 45 minutes," said Hagen. "Depression can be immobilizing to the person who's experiencing it. When I say it took me four hours to get on my shoes, I don't know what happened in those four hours."

But at the time, Hagen thought she would find a way out of her situation.

Instead, things got worse. At 6:48 a.m. on Aug. 26, 2000, Hagen, sounding weak and utterly disconnected, called 911.

"My parents have been dead in their beds for days," she said. "I've gone out of my mind … I did this really bad thing."

Police would later say that Hagen went to their beds and smothered her parents as they slept.

An Extraordinary Sacrifice

When Corash found out what her friend had done, she was shocked.

"A lot of things went through my mind that day. Was this a mercy killing? Did her and her father get into some sort of argument?" asked Corash. "Did somebody come into the house? Was she being framed? … I just wanted to find out what the truth was."

The truth, Hagen told ABCNEWS' Chris Cuomo, is that she remembers calling 911, but has no recollection of killing her parents.

"I love my parents," she said. "I just can't believe how a mind can be so messed up that it could happen. It wasn't rage, it wasn't anger, it wasn't anything like that. It's unbelievable."

Hagen said she remembers becoming delusional, receiving messages from traffic signals, television commercials, even playing cards. And she took orders from male voices, she said, which told her that smothering her parents would lead them to a better place.

The murders and her behavior leading up to them have left Hagen her virtually alone. Corash, however, was determined not just to support her friend, but to save her. She hired a defense team, mental health professionals and top criminal attorney Gerard Hanlon. She took a buyout from work. She lost friends who didn't understand her devotion. She has become Kathy's guardian. Corash also cleaned out the home of Hagen's parents, and arranged their funeral.

This past January, a judge found Hagen not guilty by reason of insanity in the murders of her mother and father. She will be confined in a maximum-security psychiatric hospital until she is evaluated and considered fit to move to a less restrictive facility.

Hagen knows she has an extraordinary friend in Corash. "She's my worldly savior, my right hand," she said.

Corash hopes that her friend will one day be freed to live a normal life under a doctor's close care.

"More than anything she gives me hope," said Corash, who visits Hagen daily. "Hope and love and she's given me the will to go on and gain courage."