Prosecutors have said they are dismissing all criminal charges against eight people who were charged in the Flint, Mich., water crisis and are restarting their investigation into one of the worst manmade public health crises in U.S. history.

The announcement of the dropped charges comes as prosecutors say they will essentially start from scratch in reviewing the water crisis in order to expand the scope of the investigation.

Michigan Solicitor General Fadwa Hammoud took over the case in January and said previous prosecutors had not taken advantage of all available evidence, according to The Associated Press.

"This week, we completed the transfer into our possession millions of documents and hundreds of new electronic devices, significantly expanding the scope of our investigation," Hammoud said in a statement.

That expanded search included seizing the cell phone and other records from former Gov. Rick Snyder (R).

Former state health director Nick Lyon was among those whose charges were dropped. Lyon was facing charges of involuntary manslaughter and accused of not quickly alerting the public of a Legionnaires’ disease outbreak while Flint used water that was not properly treated.

The outbreak of Legionnaires’, a form of pneumonia, occurred while the city used lead-contaminated water that also contained other bacteria tied to the disease. Lyon was the top official charged in the probe.

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With the announcement of the dropped charges, Lyon's attorney, Chip Chamberlain, told the AP they "feel fantastic and vindicated," but acknowledged that Lyon and others could be charged again.

In April, a federal judge ruled residents of Flint, Mich., can sue the federal government over its response to the city's drinking water crisis.

Residents have long blamed the Environmental Protection Agency (EPA) for waiting too long to intervene into state and local management of the city's water.

Flint's water troubles began in 2014 after switching its water source to the Flint River. The city no longer uses the river for its water supply.