FE brought the knife from the US apparently.
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An Italian policeman who was allegedly killed by two teenage American tourists was stabbed 11 times with a knife carried into Italy from the United States, according to police in Rome.
General Francesco Gargaro, of the Provincial Carabinieri Command, said the weapon was brought to the country by the 19-year-old suspect, Finnegan Lee Elder.
Gargaro added that some of the wounds sustained by the fallen officer, Mario Cerciello Rega, were "very big, 17 centimeters (7 inches) deep, the length of the blade."
https://edition-m.cnn.com/2019/07/29/europe/italy-police-killing-funeral-intl/index.html?r=https://edition.cnn.com/