The European Commission in 2015 opened an antitrust investigation into Google’s Android mobile operating system.

The commission said at the time that it would focus on three key aspects in its investigation including whether Google prevented hardware manufacturers from creating forked versions of Android, whether or not the search giant hindered the development and access of rival mobile apps and services by forcing OEMs to exclusively pre-install Google apps and services and finally, whether Google apps and services on Android devices have been bundled with other Google apps, APIs or services.

Sources familiar with the matter tell Reuters that EU antitrust regulators are weighing a massive fine against Google regarding the aforementioned Android points and have set up a panel of experts to give the case a fresh look.

This peer review panel, sometimes called a devil’s advocate, is typically comprised of three to four experienced officials tasked with combing over the case team’s conclusions before a final decision is made.

The publication said it is unclear if the panel has started its review yet, a process that usually takes up to four weeks (but could run longer in this instance).

The European Commission last week hit the search giant with a record $2.7 billion fine over Google’s alleged abuse of its dominant position in the shopping comparison / search results market.

Assuming the devil’s advocate panel agrees with the commission’s conclusion in the Android case, the European Commission could announce a ruling by the end of the year. A potential fine could be even higher than the $2.7 billion from a week ago.

Google in April reached an out-of-court settlement with the Russian Federal Antimonopoly Service relating to a similar dispute involving Android.