An MP for the ruling anti-establishment 5-Star Movement (M5S), Piera Aiello, is being probed for making false statements in public acts, police said Wednesday.
Aiello, 51, is a member of the Lower House.
The probe is linked to her candidacy, police said.
This is because her name no longer exists in the public registry in the town of Partanna, where she was born, because of her status as a justice witness.
Prosecutors said she had committed irregularities by standing for parliament with her birth name.
They said the name Piera Aiello had been "frozen" when she turned state's evidence.