The chief financial officer of one of Spain's greatest modern tourist attractions, the Guggenheim Museum Bilbao, was fired for allegedly embezzling nearly $800,000.

The museum has now launched legal proceedings against Roberto Cearsolo Barrenetxea, according to the Associated Press.

He had been financial director of the museum, housed in the Frank-Gehry-designed architectural wonder, since 1997.

The art museum told the wire service that it began an internal investigation earlier this month into certain financial operations after receiving a query from a regional financial tribunal.

One day later, Cearsolo sent a letter confessing to embezzling $776,000 since 1998 from two companies that are subsidiaries of the museum, according to the CBC.

Cearsolo promised to return the money within three months, according to the museum. It noted he has already returned $459,000.

According to the CBC, museum officials described the situation as an "isolated case."

The museum actually published an account of the alleged theft at the museum. It issued a dossier about how, "in order to hide the amounts stolen, [Cearsolo] altered the financial and accounting documents of both companies by manipulating the books, falsifying the contents of bank statements and altering the authorised signature."