After speaking with judiciary officials in the Aquila region where the school is located, Justice Minister Roberto Castelli said that he himself will open the investigation.
"If it is verified that the judicial sentence was pronounced disregarding specific dispositions of the legislation or the Italian Code, it could result in a disciplinary sanction," he told the newspaper La Padania.
A possible sanction of Judge Mario Montanaro, 33, will depend ultimately on the Higher Council of Justice, a body that controls the judiciary.
Italian law allows the display of crucifixes in schools. Bishop Giuseppe Betori, secretary of the Italian episcopal conference, explained that the law has not been changed "by any Parliament, much less so by the Constitutional Court."
The complaint against the image of Christ in the Antonio Silveri nursery and elementary school in the town of Ofena was lodged in court by Adel Smith, president of the Union of Muslims of Italy.
Smith, of a Scottish father and Egyptian mother, is promoter of the fundamentalist party which claims a following of just over 5,000 members. Muslim communities in Italy have criticized the group.
"Smith takes advantage of every opportunity to fight against and insult the Christian religion and its symbols," lamented Hamza Roberto Piccardo, secretary-general of the Italian Muslim communities.
Mahmoud Shrour, the only Muslim mayor in Italy, explained: "We Muslims respect others. Smith is an agitator. One cannot play politics by instrumentalizing God. All efforts at integration are now in danger."