The relic, a small bone from one of the saint's hands, had been an object of veneration in the Santa Maria degli Angeli church since Bosco became a saint nearly 80 years ago, ANSA reported.
Bosco (1815-88) was a priest who dedicated his life to the aid and education of disadvantaged youth and founded the Society of St. Francis de Sales, more commonly known as the Salesian Society.
He was canonized by Pope Pius XI in 1934.
Police in Alassio say they've opened an investigation but had no immediate leads.
Celebrity Families of 2014 [PHOTOS]