LANSING – The Michigan Attorney General's Office has dismissed all pending criminal charges arising from the Flint drinking water crisis,saying the initial investigation was bungled and it is opting to launch a new but expanded probe.

The office announced on Thursday the dismissal of charges against all eight remaining defendants, including involuntary manslaughter charges against Nick Lyon, the former director of the Department of Health and Human Services.

Charges were also dismissed against other officials from the health department, plus two former Flint emergency managers and current or former employees of the Michigan Department of Environmental Quality and the City of Flint.

Seven had earlier pleaded no contest to misdemeanors, with expectations they would cooperate with other pending prosecutions and their records would eventually be wiped clean.

Flint residents reacted with shockMinority Leader Jim Ananich, D-Flint, said he wants "to see people behind bars" over what happened in Flint.

"Words cannot express how disappointed I am that justice continues to be delayed and denied to the people of my city," Ananich said. "Months of investigation have turned into years, and the only thing to show for it is a bunch of lawyers who have gotten rich off the taxpayers’ dime."

Flint's water crisis began in April 2014, when a state-appointed emergency manager switched the city's drinking water supply from Lake Huron water treated in Detroit to Flint River water treated at the Flint Water Treatment Plant. It was a temporary, cost-saving measure, but turned out to be a disastrous mistake. The DEQ has acknowledged it failed to require needed corrosion-control chemicals