Mystery as ex-US swimming champion Jamie Cail found dead by boyfriend in Virgin Islands

An ex-US swimming champion's death is under investigation after she was found unconscious by her boyfriend.

Jamie Cail, 42, was discovered by her boyfriend, whose name has not been revealed, at their home in St John, Virgin Islands on February 21 just after midnight.

According to the Virgin Police Department, her boyfriend was at a bar that evening when he headed back home to check on Jamie.

After entering the home he tragically found her dead on the floor.

Virgin Islands Police Department said in a statement: "Upon arrival, he discovered his girlfriend on the floor.

"With assistance from a friend, the male was able to get the female to a nearby vehicle and transported the female to the Myrah Keating-Smith Clinic."

The boyfriend, along with a friend of Jamie, quickly drove her to the hospital but despite life-saving efforts the swimming star was pronounced dead.

Jamie Cail was found unresponsive at the home she shared with her boyfriend (WMUR)

Police said in a statement: "Once at the clinic, CPR was rendered and 911 was notified, however, the female succumbed to her ailment."

Cops were notified of Jamie's death at around 2:39 a.m on Tuesday, according to authorities.

The Criminal Investigation Bureau confirmed her death is under investigation.

Jamie, who was born in Claremont, New Hampshire, was a prolific swimming star who won a gold medal for a relay race in the US Pan Pacific Championships.

The ex-swimming champion was rushed to hospital but tragically died shortly afterwards (WMUR)

And during the 1998-1999 World Aquatics Swimming World Cup in Brazil, the talented swimmer won a sliver medal.

She soon moved to Huntington Beach, California, where she trained with the Golden West Swim Club and had an incredibly successful period.

The swimmer won multiple high school state championships during her time there.

In addition, she was a member of the University of Maine's women's swim team in the 2000-2001 academic year, according to the school's alumni association.

The ex-swimming prodigy was discovered dead on the floor of her apartment (Getty Images)

Friends have paid tribute to Jamie, who was hugely popular on the island, according to friends.

She worked at a local coffee shop and could talk to anyone as she had a a "huge heart."

One friend told WMUR: "Everyone from the, you know, older generational, local families to the younger people, everybody loved her."

"She had a huge heart. She was really loving and kind and well-loved and popular on the island and everybody knows her."