Four artworks linked to Renaissance master Antonello da Messina remain missing after thieves broke into a museum in the Sicilian city of Messina and made off with six works during a procession on the night of Aug. 15.
Two of the stolen pieces were later found near the museum, while the remaining four, estimated to be worth millions of euros, have yet to be recovered.
According to Italian news agency ANSA, three or four people with their faces concealed by helmets entered the museum shortly before 10:00 p.m. local time and took the artworks.
Among the stolen pieces were three panels from the 1473 San Gregorio Polyptych, a multi-panel work attributed to Antonello da Messina, as well as a double-sided panel featuring "Madonna and Child" and "Christ in the Pieta."
The thieves are believed to have noticed people around the museum while making their escape and left two of the stolen works on a wall outside. The pieces were found shortly afterward.
Four works remain unaccounted for, with their combined value estimated at millions of euros.
Italy's Culture Minister Alessandro Giuli said he felt "astonishment and sadness" over the incident and expressed readiness to cooperate with the authorities handling the case.
Sicilian regional government President Renato Schifani described the theft as an "extraordinarily serious crime" and an "unacceptable attack on universal cultural heritage."
The Messina Prosecutor's Office has opened an investigation into the theft.
Antonello da Messina was a prominent 15th-century Sicilian painter known particularly for his portraits and religious works.