Someone stole the head of a leatherback sea turtle that washed up on the shore at Cedar Beach before researchers got there Thursday morning.

Greg Watkins-Colwell, collection manager at the Yale Peabody Museum in New Haven, showed up with a small team Thursday to collect the dead turtle for study, but found that someone had taken the head during the night.

“It was here yesterday,” Watkins-Colwell said.

The giant carcass was loaded anyway onto the back of a pickup truck and taken to the Peabody Museum. Milford Public Works employees used a payloader to lift the turtle into the museum staff's vehicle. Scientists will study it to try to determine its age, sex and how it died. Then its skeletal remains will be preserved as part of the museum’s collection.

The leatherback sea turtle is an endangered species that is known to live in Long Island Sound. Neighbors found the turtle Tuesday, dead and washed up on Cedar Beach, which is near the Connecticut Audubon Coastal Center. It weighed about 400 pounds and measured six feet from its front flipper to its back flipper.

There are probably similar turtles in the Sound right now, Watkins-Colwell said.

The scientists couldn’t speculate on how the turtle died but said this type of turtle eats jelly fish, and sometimes mistake plastic bags for jelly fish.

Watkins-Colwell said a similar turtle washed up on the beach in Fairfield about 10 years ago.