From December 1960 to July 1961, Petrucci was assessor in charge of the "new town plan", in the minority municipal government led by Urbano Cioccetti.

[citation needed] Two years later, Della Porta resigned, and on 13 March 1964 Petrucci was elected mayor, at the head of a centre-left government.

[citation needed] In the local elections of 12 June 1966, the centre-left obtained an absolute majority in the municipal council of Rome and Petrucci was re-elected mayor.

Petrucci therefore resigned as mayor on 13 November 1967, assuming the post of councillor for the budget in the new council led by Rinaldo Santini.

On 20 January 1968 he was indicted and placed in preventive detention for a few months, due to an incident linked to the management of the National Maternity and Childhood Work (OMNI) agency of which he had previously been commissioner.