Intruders broke into the family tomb of legendary conductor Arturo Toscanini, opening his daughter's coffin and damaging her tombstone, police said Saturday.

The motive was unclear, given that nothing was believed to have been stolen, but police didn't rule out the possibility that the culprits were searching for jewelry.

The damage was limited to the tomb of Wanda Toscanini Horowitz, the daughter of the conductor and wife of the pianist Vladimir Horowitz.

The intruders left no clues as to their identities, Police Col. Marco Rizzo said.

"It surely wasn't an act of vandalism," he said, citing the fact that they didn't leave graffiti. "There were at least two people involved, maybe a third person. We don't know."

The break-in happened Thursday night, although it wasn't noticed until the following day. The culprits entered, pulled open a grate to the underground chamber, but ignored Toscanini's coffin.

Instead, they smashed a marble tombstone covering the coffin of Wanda Toscanini Horowitz, who died in 1998. They opened the coffin, then left, Rizzo said. He said it was possible the intruders may have been hunting for jewels.

Rizzo said the investigation was ongoing, but there were no suspects.

In addition to Toscanini and his children, Horowitz is also buried in the tomb.

Toscanini was born in Parma in 1867, and showed virtuosic musical talent as a young man. He went on to conduct important operatic premieres, among them Giacomo Puccini's "La Boheme" in 1896.

Toscanini was chief conductor at Milan's La Scala, then moved to the United States in 1908 to lead the Metropolitan Opera . His career continued to flourish, until he became among the most renowned names in music of his era. He died in New York in 1957, and was buried in Milan.