FLINT (WWJ/AP) – Michigan’s attorney general is announcing more criminal charges in the Flint water investigation.

Attorney General Bill Schuette has scheduled a news conference for 10:30 a.m. Tuesday. Reports indicate four people will be charged, including two former emergency managers of Flint.

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Nine people so far have been charged in an investigation of Flint’s lead-tainted water system and an outbreak of Legionnaires’ disease. Those nine are eight current or former state employees and a Flint water plant employee.

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In October, an attorney for Nick Lyon, the head of the Michigan health department, said his client is a target of Schuette’s investigation. Lyon hasn’t been charged and still leads the agency.

Flint’s water system became contaminated with lead because water from the Flint River wasn’t treated for corrosion for 18 months. The water ate away at a protective coating inside old pipes and fixtures, releasing lead.

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