One of Medardo Rosso’s masterpieces, a bronze sculpture entitled Bambino Malato (1893-95), has been stolen in broad daylight from Rome’s Galleria Nazionale d’Arte Moderna (GNAM), La Repubblica reports.

Authorities have explained that the theft took place last Friday around 4:30 pm, while the museum was open to the public. The bronze bust—whose value was confirmed to be €500,000 by the museum director, Maria Vittoria Marini—was sitting on a pedestal near the entrance of a room, in the right wing of the museum.

According to ARCA, the Italian Ministry of Culture has declared that the CCTV and alarm systems at the museum were fully operational, and that Italy’s military police for the protection of cultural heritage (TPC) has assumed command of the investigation.

TPC officers are currently interviewing museum staff, as well as reviewing CCTV camera footage to establish the details surrounding the theft.

This is not the first time that thieves have targeted the Rome museum, which has been criticized over securities issues. According to La Repubblica, two works by Vincent van Gogh and one by Paul Cezanne were stolen from the GNAM in 1998. The three works were later retrieved.

Medardo Rosso is a reputed Italian sculptor active during the Post-Impressionist period. Considered by many to be the “Italian Rodin” and thought to have been a key influence on Constantin Brancusi, Rosso is well-known for his bronze, plaster, and wax sculptures that depict everyday characters in half-formed fashion, as if they were still shaping up or dissolving. His maverick style, which broke all the traditional conventions of the medium, earned him the reputation of being, alongside Auguste Rodin, the first truly modern sculptor.