Shortly after former District of Columbia Councilmember Kwame Brown pleaded guilty to bank fraud and campaign finance violations on June 8, U.S. Attorney Ronald Machen Jr. had a message for the city’s elected officials: We’re watching.

In the past year, Machen’s office brought charges against Brown and former Councilmember Harry Thomas Jr., both of whom resigned before pleading guilty to their respective crimes and facing jail time. An ongoing probe into Mayor Vincent Gray’s campaign activities has so far netted two guilty pleas from former campaign aides.