(CNN) Authorities want to know why three fake legs have been left at different times at a memorial to a man who died after he was bitten by a shark off the Massachusetts coast.

The most recent leg was left at Newcomb Hollow Beach a week ago Saturday, Lt. Michael Hurley of the Wellfleet Police Department said.

The fake legs began showing up in March, Hurley said.

Arthur Medici died after a shark attack in Massachusetts.

Arthur Medici, 26, a native of Brazil who was living in Revere, Massachusetts, died in September 2018 in what officials said was believed to be the first fatal shark attack in Massachusetts in more than 80 years. Medici and another man were boogie boarding 30 yards off the beach.

CNN affiliate WBZ reported in the days after the attack off Cape Cod that the shark bit Medici's legs

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