Notorious attack on Michelangelo's Pietà occurred on 21 May 1972.

51 years ago today, a Hungarian man called Laszlo Toth climbed over an altar rail in St Peter’s Basilica and attacked Michelangelo’s Pietà with a geologist's hammer, while screaming: “I am Jesus Christ – risen from the dead.”

The Renaissance masterpiece, which portrays the Madonna holding the dead body of Jesus after he was taken down from the cross, suffered extensive damage from Toth's approximately 15 hammer blows.

The attack, which took place in front of horrified pilgrims, saw Toth knock the Madonna's left arm off at the elbow, chipping off an eyelid and a significant part of the statue's nose.

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The 33-year-old Toth was quickly restrained by bystanders, including the American sculptor Bob Cassily who hit the assailant several times before pulling him away from La Pietà.

The chapel floor was littered with around 100 fragments from the statue which Michelangelo carved from a single block of Carrara marble before it was unveiled in 1499.

Some of those present pocketed these chipped remains as "souvenirs," with at least one person subsequently repenting and sending the ill-gotten memento back to Rome anonymously from the United States.

Restoration of the Pietà

The Vatican was faced with a dilemma regarding the restoration, with art historians divided on how to proceed.

Some experts said the statue should remain in its damaged state, others argued that it should be fixed but distinguishing clearly the restored parts from the original.

In the end the Vatican opted for an “integral” procedure invisible to the naked eye, according to Reuters, resulting in one of the most delicate and complex art restorations in history.

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The operation saw restorers spend more than five months identifying all the fragments, some minuscule, before beginning to piece them together invisibly with glue and powder ground from Carrara marble.

When the painstaking restoration was complete, about 10 months after the attack, the Pietà went back on display - this time behind bulletproof glass.

What happened to Laszlo Toth?

In view of his apparent insanity, Toth was never charged with the crime. In January 1973 he was committed to a psychiatric hospital in Italy.

Toth was released in February 1975 and deported from Italy to Australia, where he had studied prior to the Pietà attack.

Australian authorities did not detain him and he faded into oblivion, reportedly living a hermit-like existence in a remote part of New South Wales. Toth died on 11 September 2012.