The prosecutor opened a case file over the absences following a petition from the consumers' association Codacons, Ansa reported on Wednesday.
While no specific officers have been named, the probe centres around the hundreds which called in sick on New Year’s Eve.
A total of 835 municipal police officers - 83.5 percent of the Rome force - failed to show up for their shifts. The majority claimed they suddenly fell ill, while dozens said they couldn’t come to work because they had donated blood that day.
The increased public safety risk as around 600,000 revellers took to the streets did not go unnoticed, with Prime Minister Matteo Renzi demanding action.
“I read that 83 out of 100 Rome police did not work due to 'illness' on December 31st. This is why we are changing government employment laws in 2015,” the premier tweeted on January 2nd.
Rome Mayor Ignazio Marino said those responsible for “unjustifiable absences” must be held to account.
The first 30 disciplinary letters were issued on Monday evening, with 90 officers at risk of being sacked, Corriere della Sera said.