delve into ...

「〜を徹底的に調べる、調査する」。

The Guardianの記事、'Italian government battles with Florence for Michelangelo's David - Government lawyers produce nine page document as 'conclusive' proof that the sculpture belongs to the state' by Tom Kingtonから。

'A fierce row has erupted over the ownership of Michelangelo's David between the Italian state and Florence, the city where the masterpiece is on display.

A symbol of the Florentine Republic's defiance of its enemies, including Rome, when erected in 1504 at the entrance to Palazzo Vecchio, the town hall, Michelangelo's portrayal of the slayer of Goliath has remained a mascot for proud locals long after the unification of Italy.

But after delving into centuries-old archives, two lawyers commissioned by the government of Silvio Berlusconi have produced what they call conclusive evidence that the renaissance masterpiece belongs not to Florence, but to the Italian state.

In a country where local loyalties often triumph over national pride, the reaction in Florence was fast and furious, starting with the mayor. "With all due respect to Roman lawyers," said Matteo Renzi, "the unquestioned documents in the possession of the city and the state are clear: David belongs to Florence."

In a nine-page document, the legal team from Rome argues that the state of Italy, not the city of Florence, is the legal successor to the Florentine Republic, which funded the purchase of the sinuous, sling-bearing David that Michelangelo daringly carved from an awkwardly sized block of Carrara marble that had lain unused in Florence for decades.'