Updated

Michigan's attorney general filed more criminal charges Tuesday in the investigation of lead-tainted water in Flint, targeting two former state-appointed emergency managers who were running the troubled city and had key roles in making changes to the supply that caused the crisis.

Former emergency managers Darnell Earley and Gerald Ambrose were each charged with four crimes, including conspiracy. Attorney General Bill Schuette said they committed Flint to $85 million in bonds to help build a new water pipeline to Lake Huron while at the same time using a city water plant that was not equipped to treat water properly from the Flint River.

Schuette also charged former Flint city employees Howard Croft and Daugherty Johnson with conspiracy and false pretenses. Croft was the public works director from December 2011 to November 2015. Johnson was Flint's utilities director.

Johnson's attorney, Edwar Zeineh, said his client will plead not guilty. The others and their lawyers couldn't immediately be reached for comment.

Flint's water system became contaminated with lead because water from the Flint River wasn't treated for corrosion for 18 months, from April 2014 to October 2015. The water ate away at a protective coating inside old pipes and fixtures, releasing lead.

During a news conference, Schuette said the water debacle was a result of "arrogance, disdain and a failure of management."

The latest charges bring to 13 the number of people who have been charged in the investigation of Flint water and an outbreak of Legionnaires' disease. The other nine are eight current or former state employees and a Flint water plant employee.

Schuette said the investigation isn't over, although "we are closer to the end than we are to the beginning."