The purpose of the raid is still not clear - one theory is that the Italian authorities claimed the coins seized had been illegally exported from Italy.
The police are reported to have seized two coins from the 19-lot classical Greek offering and arrested and temporarily detained Arnold-Peter Weiss, a renowned hand surgeon and a Trustee of the American Numismatic Society, who is a partner in the firm and thought to have been the vendor.
The sale was part of January's multi-million dollar New York coin sales series and was scheduled for the same day as the landmark Prospero auction, reported here.
The Nomos/CNG sale was billed as "Selections from the Cabinet W" and both of the coins reported as seized were struck in late 5th century BC Sicily.
ATG managed to reach Weiss on the phone, but he said that he could not comment for legal reasons. Nomos were no more forthcoming. However, the eyewitness account came from online magazine Coin World.
One of the coins reported as seized is the celebrated decadrachm of the Sicilian city of Acragas struck in 409-406 BC. There are now 12 known examples, an increase on the six recorded by the scholar A.J. Seltman in 1948. The oldest provenance relates to the one at Munich which has been there since the 16th century.
The one reported as seized is listed in the catalogue as having been in a collection in London since the 1960s.
The other coin reported as seized was the decadrachm struck in the city of Katane, also in Sicily, at about the same time. They had estimates of $2.5m and $300,000 respectively.
Three other coins originally struck in Sicily were not seized.
Could it be that the seizures are linked to the stricter legislation concerning coins originally from Italy and imported into the United States, which became law on December 1?