The FBI is joining a U.S. investigation into Flint, Michigan's water contamination crisis, a spokeswoman for the U.S. Attorney's Office in Detroit said on Tuesday.

Gina Balaya, a spokeswoman for the U.S. Attorney's Office in Detroit, said in an email that federal prosecutors in Michigan are "working with a multi-agency investigation team on the Flint water contamination matter, including the FBI, the U.S. Postal Inspection Service, the EPA's Office of Inspector General ... and the EPA's Criminal Investigation Division."

The city was under the control of a state-appointed emergency manager when it switched its source of tap water from Detroit's system to the Flint River in April 2014.

The more corrosive water from the river leached more lead from the city pipes than Detroit water did.

Last week, Michigan Attorney General Bill Schuette named a special prosecutor and investigator to look into possible crimes stemming from the matter.