A Massachusetts marine biologist who examined a 13-foot great white shark carcass found ashore near the Rhode Island state line wasn't able to determine how the shark died.

Massachusetts environmental officials say state biologist Greg Skomal performed a necropsy on the shark Saturday and found no signs of trauma. Officials say what happened to the shark may never be clear. A fisherman found the carcass Saturday morning on a rocky area on the Westport shore near Little Compton, R.I.

Little Compton officials closed nearby beaches but reopened them Sunday. Police sent out a boat patrol Sunday to watch for other sharks. Officials say they plan to leave the shark's carcass where it is because it's too heavy to remove. They say it weights an estimated 1,500 pounds.

[Via AP]