A woman's dead body was found floating inside a trash bag off the coast of Pinellas County, Florida. The FBI has launched an investigation as the remains were found in federal waters.

The trash bag was spotted about 13 miles west of Egmont Key on Saturday, said Erik Villa, a spokesperson with the U.S. Coast Guard District 7, the Tampa Bay Times reported. The woman's body was wrapped in a canvas bag inside the trash bag.

The body was first spotted by fishermen before law enforcement agencies got involved, WFLA reported.

Some eyewitnesses said they were spear-fishing and went for a dive when they came across the trash bag in the water. They initially thought it contained trash but realized something else was in it when they went near to inspect.

The fishermen alerted authorities after they cut the plastic bag open and found the canvas bag inside. They reportedly saw skin and what appeared to be a bra strap or bikini.

The body was recovered after officials from multiple agencies, including the Coast Guard and the St. Petersburg Police Department, arrived at the scene.

The woman appeared to be middle-aged. The FBI is looking into the case, Andrea Aprea, a spokesperson for the Tampa office, said. The woman's identity or the circumstances surrounding her death were not revealed.

It was also unclear how the body reached 13 nautical miles west of Egmont Key, located in the mouth of Tampa Bay.

In a similar incident last year, a woman's remains were found in McKay Bay in Tampa, Florida. Officers said fishermen first spotted what appeared to be a human leg floating near the 22nd Street Causeway Bridge in McKay Bay. More body parts were eventually found and recovered from the same area. The woman was identified as Stephanie Crone-Overholts and her death was ruled a homicide.

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Representation. The lights of a police car. tevenet/Pixabay