The events of that night, July 24, 1969, on Mustang Island have baffled investigators for 40 years. One girl died, and it so haunted her friend that it may have led her to kill herself decades later.
Genevieve Duncan met her daughter May on the stairs of the two-story beach house. May said the cry came from her friend, Caroline Harte. The mother heard a door slam, and found a terrifying sight downstairs: Caroline was gasping and bleeding on the bed, suffering from a stab wound to the heart. By the time they dressed to take her to a hospital, Caroline was dead.
The case is the oldest unsolved slaying in Nueces County, which includes Corpus Christi along the Texas Gulf Coast. The knife was never found. No motive was clear and no arrests were ever made.
Caroline's father, then-publisher of the San Antonio Express and Evening News, had an unsettling premonition after his brother, Edward, then publisher of the Corpus Christi Caller-Times, called to relay the news. "Sometimes, as we walked around in shock, I remember thinking to myself: This is a crime that will never be solved," said Houston Harte, whose father was a founder of Harte-Hanks Newspapers Inc.
"And I was right about that."
The sheriff's department case file includes a fading color snapshot of a smiling Caroline, her red hair parted down the center and pulled back behind her ears, a sky-blue striped T-shirt whose color matches her eyes. It documents every clue, none of which lead to the killer.
A few days before the attack, the girls' bathing suits, left outside to dry in the sea breezes at the beach house, turned up missing. No one could ever link the theft to the killing. Detectives dusted the door Mrs. Duncan heard slam and the rest of the house for fingerprints, but turned up nothing.
A dock worker and a service station attendant were given polygraph tests. Cops questioned a paper boy, drifters, surfers, maintenance workers and people with various illegal drug connections. The son of a military man from a nearby naval air station was questioned in Florida. A suspicious man with binoculars was questioned. Turns out he was a birdwatcher.
Window peepers were picked up, sex offenders tracked down, obscene phone callers located. Three weeks after the slaying, a car with Minnesota plates was spotted with a bloody knife on the back seat. It was fish blood.
Police in San Antonio tracked down a guy known as Freddy Flashlight, a convicted burglar on probation, but he denied involvement and offered to take a polygraph. Acting on a tip, they found a man in Rockport who was picked up for stealing women's clothing and shredding underwear with a knife. No dice.
A Buick mechanic saw news clippings about the slaying in the back seat of a car he was working on and alerted police. It turned out the daughter of the car's owner knew Caroline and had an interest in the case. Even potential ties to the Charles Manson slayings were investigated, but tossed aside.
Detectives hauled in a 23-year-old man with scratch marks on his right arm that an informant said had been acting strange, singing and dancing alone and offering to pay friends so he could "score" with a woman. He could account for the day before and the day after Caroline's slaying, but not the day of her death - or the scratches.
But he didn't have a criminal record. His attorney refused a request for a lie detector test. Authorities had no fingernail scrapings from Caroline to check for DNA, unknown in 1969.
He was let go.
With the mystery unsolved, May Duncan was left to live her life carrying the memory of her friend's brutal death. She married, but Caroline's legacy soon became apparent to her spouse, who learned of the slaying not long after they met.
"Intuitively, I knew that was a major part of her life," said Skip Doty, May's husband of 21 years. "At the same time, I didn't want to pry."
They never had children, something her husband believes was connected to the killing.
"It gnawed on her the rest of her life," he said. "I think it kind of gnawed on the whole family. It was one of those events you can't imagine happening."
When she was interviewed by police after Caroline's death, May told authorities they were reading "How Green Was My Valley," a novel about a Victorian-era mining family in Wales. Some time after 11 p.m., Caroline turned out the light and they both went to sleep.
Caroline's cry woke her. May called to her friend to be quiet and got a moan in response.
"I went over to her because I thought she was dreaming," she told officers.
May went to find her mother upstairs and stayed there while mom and dad checked on Caroline.
"A short time later my parents came back upstairs and told me Caroline was dead, and that she had a wound in her stomach," she told detectives, describing the incision between Caroline's third and fourth ribs that pierced her heart.
Doty said his wife met with Harte's parents, now in their 80s, in San Antonio about 10 or 12 years ago. They got the sense she never believed she wasn't still considered a suspect. She was one of the first people interviewed, but police were quickly convinced May didn't kill her friend.
"We never thought she accepted fully that we didn't suspect she had something to do with it," Houston Harte said. "We worked to convince her of that. But that was not a widely agreed to theory and she suffered greatly from that suspicion."
She slipped in and out of depression for much of her life, her husband said. And while she could have periods of joy, he was wary. He kept the kitchen knives, for instance, "more dull than they should have been." He decided keeping a gun in the house was a bad idea.
She bought one anyway, without his knowledge, and in 2006, Doty found his wife in their orchard, dead from a bullet she had fired herself.
The last entry in a nearly 6-inch-thick pile of investigators' notes and crime scene photos is dated June 3, 1970, although Nueces County Sheriff's Lt. William Edge said sheriff's detectives 15 or 20 years ago made a round of calls checking on suspects who initially were questioned.
Even as investigators consider whether to pry into the case again, there isn't much to review. The house has changed owners, witnesses have passed away, files have been read and re-read. Years have gone by without so much as a tip about what might have happened to Caroline Harte.
"This case, if solved, will be because somebody told somebody, or somebody someday is going to want to get it off their chest at the end," Edge said. "That's how I see it."