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Crime News Dateline

Beloved School Administrator Found Dead During Scuba Trip, But Was It an Accident or Murder?

As an experienced diver, Shelley Tyre had been looking forward to an easy dive in Tortola to explore twin ship wrecks with her husband, David Swain. Tragically, she would never return from the trip.

By Jill Sederstrom

It was supposed to be the trip of a lifetime. 

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Catch up on Dateline: Unforgettable on Peacock or the Oxygen App.

Beloved school administrator Shelley Tyre and her dive shop owner husband, David Swain, planned to spend a week away from the busyness of everyday life, sailing and snorkeling near the Caribbean island of Tortola with another couple. 

But on one seemingly easy dive, Shelley never surfaced and was found dead at the bottom of the ocean with broken gear. Was it a tragic accident or a sinister murder? 

“What happened some 80 feet down? I’m still not sure,” reporter Dennis Murphy shared in Oxygen’s Dateline: Unforgettable. “Prosecutors called it murder. I call it one of the most confounding investigations I’ve ever covered.” 

Who was Shelley Tyre? 

At just 5 feet tall, Shelley was a vivacious and well-loved middle school headmaster at the prestigious Thayer Academy in Boston.

“She was effervescent. She was always on the move, always on the go,” one parent at the school remembered. 

In the early ‘90s, Shelley found love with Rhode Island dive instructor David Swain after the pair met during a boat outing. 

“It was a rocky day, a little bumpy. A couple of the big, tough guys got seasick, so I paired up with her and went back in,” David recalled of their first meeting. “She had a lot of spunk and I was showing her fish in a way that she had never seen them before. So, that’s what got things started.” 

Three years later, the couple got married, and although they never had any children of their own, Shelley was a devoted stepmother to David’s two children from a previous marriage. 

How did Shelley Tyre die? 

The biggest challenge for the couple was Shelley’s hours-long commute each day from their coastal home in Jamestown, Rhode Island to Boston. She’d often leave at dawn and get home late each night.

“Without question, we were struggling about the time apart,” David said. 

The couple was hoping to reconnect and have some fun in the sun in March 1999 and planned a picturesque sailing vacation in Tortola with another couple and their son. The group rented a sailboat and set out on a postcard-worthy trek through some of the area’s most astonishing scuba diving sites. 

On the morning of March 12, 1999, the group set out to Cooper Island, where they planned to explore a site known as the Twin Wrecks, the final resting place of two ships that sank to the ocean floor and now serve as a makeshift home for tropical fish and wildlife. 

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Shelley and David planned to head down together to explore the site first, acting as what’s known as scuba diving buddies. 

Despite the well-known buddy rule, David said once they got underwater, the two split up. While he went to document the wildlife with his camera, Shelley set about to count the fish underwater.

When David surfaced about 35 minutes later and returned to the boat, he wasn’t worried that Shelley had yet to return. One of their traveling companions, Christian Thwaites, hit the water and soon made a troubling underwater discovery. 

Thwaites found Shelley’s fin sticking straight up in the ocean floor and then discovered Shelley, an experienced diver, lying face up with her eyes wide open on the ocean floor near the wreckage.

“He surfaces screaming,” David recalled. 

David hopped in the dingy and rode out to his friend. He discovered that Thwaites was carrying Shelley’s body and David, a trained EMT, attempted to perform CPR before declaring his wife dead. 

Was Shelley Tyre’s death an accident or murder?

After performing an autopsy, the medical examiner ruled that Shelley’s drowning death had been an accident and David returned home to Rhode Island. But those who knew him — including Shelley’s grieving parents, Richard and Lisa Tyre — claimed they were struck by the limited details he told them about what happened underwater and his seemingly emotionless reaction to her death.

In 2002, Richard and Lisa filed a wrongful death lawsuit in civil court against their former son-in-law, who had inherited $600,000 after his wife’s death. Although there were no witnesses or DNA evidence, the couple was troubled by Shelley’s broken scuba gear that was later recovered from the ocean floor. 

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Her snorkel was missing its mouth piece, the strap of her scuba mask had been broken, and the pin designed to keep the strap in place was also missing. Then there had been her fin sticking straight up from the ocean floor with its foot strap pulled back, like perhaps someone had forced her out of the fin.

The Tyres' attorney argued in court that David had attacked his wife from behind, turned off her air supply, and then held her down until she drowned. David — who claimed he lacked the financial resources to effectively defend himself and had an attorney who got ill and had to step back from the case — put forth a limited defense. 

David addressed the jury himself and called his adult daughter to the stand, who testified how distraught her father had been in the wake of the tragedy.

The jury wasn’t convinced, however, and David was found responsible for Shelley’s death in the civil court and ordered to pay $3.5 million in damages. 

Was David Swain convicted in Shelley Tyre’s death?

It wasn’t long before authorities in Tortola took notice of the verdict and decided, eight years after Shelley’s death, to charge David with murder in a criminal court.

Prosecutors laid out much of the same case used in the civil proceedings. They argued that in the months before Shelley’s death, David was pursuing another woman, a chiropractor and seasoned diver named Mary Basler. 

Basler testified that one night while having wine and dinner at her home, David had tried to kiss her, but she rejected his advances because he was a married man. Prosecutors also pointed to letters David had written Basler before Shelley’s death in which he called her his “soulmate.” 

In one letter, written five months before Shelley’s death, David seemingly referenced his difficult predicament. 

“Life has definitely gotten more complicated,” he wrote. “I’m wanting to be with you but I can’t change this mess I’ve got anytime soon.”

David’s dive shop had also been struggling and relied on extra financial help from Shelley, who had recently taken a new job that included a pay cut to spend more time with her husband.

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According to prosecutors, under the couple’s prenuptial agreement, neither would get any money from the other if they divorced. However, based on Shelley’s will, David stood to inherit her whole $600,000 estate in the event of her death.

"This man here, his wife is killed, and all his dreams came true. All his dreams came true,”  prosecutor Terrance Williams told the jury.

They argued that according to the amount of air left in Shelley’s tank, she died just eight minutes into her dive at a time when, by David’s own admission, he had been with his wife. 

Thwaites also took the stand to testify that David performed only limited CPR and when Thwaites tried to perform the rescue breaths he “stopped me, told me specifically to stop,” according to The Jamestown Press

Thwaites also testified that David repeatedly said he wanted to donate his wife’s scuba gear and told him not to send a “Mayday” call for help.

The defense argued that David had no history of violence and disputed the prosecution’s timeline, noting that Shelley had historically used less air than the average diver. By the time Shelley died, they argued, David was hundreds of yards away exploring a reef. 

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They believed Shelley, who’d been bothered by bruising on her foot, took off the fin herself and stuck it in the sand so she could retrieve it later. Sometime after David left, she must have panicked and began to shed her diving gear, a common if not illogical response when divers get panicked.

They even pointed to entries in her dive log where she admitted to getting panicked on past dives. 

David also took the stand to insist he hadn’t killed his wife. 

“I did not, could not, would not dream of taking the rock of my life out of the world,” he testified. “That’s just … No, I did not.” 

After hearing both sides, a jury convicted David of murder and he was sentenced to 25 years behind bars. But just less than two years later, in 2011, an appellate court ruled that the trial judge had given the jury instructions that favored the prosecution and overturned the verdict.

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Furthermore, they ruled too much time had passed since Shelley’s death to retry the case and David was set free.

Where is David Swain today?

Swain returned to Jamestown, Rhode Island where he lived until he died in 2022 at the age of 66. 

David told Murphy before his death that he still thinks about his wife “almost every single day.”