FILE - In this March 21, 2016 file photo, the Flint Water Plant water tower is seen in Flint, Mich. Prosecutors dropped all criminal charges Thursday, June 13, 2019, against eight people in the Flint water scandal and pledged to start the investigation from scratch. The defendants include Michigan's former health director, Nick Lyon, who was charged with involuntary manslaughter. He was accused of failing to timely alert the public about an outbreak of Legionnaires' disease that occurred in 2014-15 when Flint was drawing improperly treated water from the Flint River.  (AP Photo/Carlos Osorio, File)

DETROIT (AP) — Prosecutors dropped all criminal charges Thursday against eight people in the Flint water crisis and pledged to start from scratch the investigation into one of the worst man-made environmental disasters in U.S. history.

The stunning decision came more than three years — and millions of dollars — after authorities began examining the roots of the scandal that left Flint's water system tainted with lead. Michigan Solicitor General Fadwa Hammoud, who took control of the investigation in January after the election of a new attorney general, said "all available evidence was not pursued" by the previous team of prosecutors.

Officials took possession this week of "millions of documents and hundreds of new electronic devices, significantly expanding the scope of our investigation," Hammoud and Wayne County prosecutor Kym Worthy said in a statement.

The efforts "have produced the most comprehensive body of evidence to date related to the Flint water crisis," they said, putting investigators "in the best possible position to find the answers the citizens of Flint deserve."

Hammoud's team recently used search warrants to get state-owned mobile devices of former Gov. Rick Snyder and 66 other people from storage.

Among those who had charges dismissed: Michigan's former health director, Nick Lyon, who was accused of involuntary manslaughter for allegedly failing to alert the public in a timely fashion about an outbreak of Legionnaires' disease when Flint was drawing improperly treated water from the Flint River in 2014 and 2015.

The dismissal came a day before a judge planned to announce whether a 2018 decision to send Lyon to trial would stand. Dropping the charges with just hours to spare killed the possibility of an adverse ruling and still gives prosecutors the freedom to haul Lyon into court again.

Nonetheless, defense attorney Chip Chamberlain said they "feel fantastic and vindicated."

"We're confident that a just and fair investigation, done properly, will yield no evidence of any criminal wrongdoing," he said.

Hammoud said she would not speak to reporters until after a June 28 town hall-style meeting with Flint residents. Her boss, Michigan Attorney General Dana Nessel, said a "fearless" team was still on the case.

"Justice delayed is not always justice denied," Nessel said in a statement.

Some residents were skeptical.

"We don't know if new charges will be filed," LeeAnne Walters, who is credited with exposing the lead contamination, told The Associated Press. "It feels kind of degrading, like all that we went through doesn't matter. Our city was poisoned, my children have health issues and the people responsible just had all the charges dropped against them."

While waiting for a new pipeline to bring water from Lake Huron, Flint, a majority-black city of 100,000, pulled water from a river without treating it to reduce corrosive effects on old pipes. Lead contaminated the distribution system in a community where 41% of residents are classified by the government as living in poverty.

Because of its poor finances, Flint was being run by financial managers appointed by Snyder. The uproar over water quality reached a peak by fall 2015, when a doctor reported high levels of lead in children, which can cause brain damage.

Some experts also have linked the water to Legionnaires' disease, a type of pneumonia caused by bacteria that thrive in warm water and infect the lungs. People can get sick if they inhale mist or vapor, typically from cooling systems.

Flint's water no longer comes from the river and has significantly improved, but some residents are so distrustful that they continue to use bottled water.

The criminal probe began in 2016, when Bill Schuette was attorney general. He hired a Detroit-area lawyer, Todd Flood, as special prosecutor. Andy Arena, the former head of the FBI in Detroit, was a key investigator.

No one is behind bars. Seven of 15 people charged pleaded no contest to misdemeanors. Their records will eventually be scrubbed clean.

Charges were pending against eight people, including former Michigan chief medical executive Eden Wells and two men, Gerald Ambrose and Darnell Earley, who were state-appointed emergency managers in Flint. Like Lyon, Wells was charged with involuntary manslaughter.

"We understand that there will be further investigation, but do not expect it to justify any further prosecution relative to her," Wells' attorneys, Steven Tramontin and Jerold Lax, said.

Through March, the investigation and prosecution had cost about $9.5 million, records show. State agencies separately have spent millions of dollars to provide defense lawyers to public employees.

Hammoud dismissed Flood in April and put together a new team. Flood told Detroit television station WJBK on Thursday that he wishes "all the luck in the world" to Hammoud, but he did not directly address the dismissal of cases that he had filed.

"We had an experienced, aggressive and hard-driving team. Everything we did was for the people of Flint," Schuette, Flood's former boss, said on Twitter.

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Follow Ed White at http://twitter.com/edwhiteap

FILE - In this Oct. 12, 2015, file photo Flint, Mich., Director of Public Works Howard Croft speaks about the two-week target for switching Flint's water source back to Detroit during a news conference at City Hall in Flint, Mich. Prosecutors stunningly dropped all criminal charges against Croft, Thursday, June 13, 2019 and seven others in the Flint water scandal and pledged to start the investigation from scratch. (Jake May/The Flint Journal-MLive.com via AP, File)
FILE - In a Monday, Aug. 6, 2018 file photo, Dr. Eden Wells listens to closing arguments from special prosecutor Todd Flood during the preliminary examination of Wells at Genesee County District Court in Flint, Mich. Prosecutors stunningly dropped all criminal charges against Wells, Thursday, June 13, 2019 and seven others in the Flint water scandal and pledged to start the investigation from scratch. (Jake May/The Flint Journal via AP, File)
FILE- In this March 15, 2016, file photo, former Flint, Mich., Emergency Manager Darnell Earley appears before a House Oversight and Government Reform Committee hearing, in Washington. Prosecutors stunningly dropped all criminal charges against Earley, Thursday, June 13, 2019 and seven others in the Flint water scandal and pledged to start the investigation from scratch. (AP Photo/Andrew Harnik, File)
FILE - In this Aug. 20, 2018, file photo, Nick Lyon, director of the Michigan Department of Health and Human Services, listens closely as Genesee District Judge David J. Goggins gives his decision during Lyon's preliminary examination at Genesee District Court in Flint, Mich. Prosecutors say they're dismissing all criminal charges against eight people in the Flint water scandal and starting the investigation over again. The eight people include former Michigan health director Nick Lyon. He was accused of failing to timely inform the public about an outbreak of Legionnaires' disease when Flint was using improperly treated water from the Flint River in 2014 and 2015. The outbreak occurred at the same time that the city's water system was contaminated with lead. Lyon was the highest-ranking official to be charged in the investigation. (Jake May/The Flint Journal via AP, File)
FILE--In this March 13, 2017, file photo, Nancy Peeler, director of the Michigan Department of Health and Human Services Program for Maternal, Infant, and Early Childhood Home Visiting, sits in the courtroom of Judge Jennifer J. Manley at the Genesee District Court in Flint, Mich. Prosecutors stunningly dropped all criminal charges against Peeler, Thursday, June 13, 2019 and seven others in the Flint water scandal and pledged to start the investigation from scratch. (Jake May/The Flint Journal-MLive.com via AP, File)
FILE--In this Aug. 22, 2018, file photo Patrick Cook listens on as Special Prosecutor Todd Flood questions U.S. Environmental Protection Agency whistleblower Miguel Del Toral, at the Genesee District Court in Flint, Mich. Prosecutors stunningly dropped all criminal charges against Cook, Thursday, June 13, 2019 and seven others in the Flint water scandal and pledged to start the investigation from scratch. (Jake May/The Flint Journal via AP)
FILE--In this Jan. 25, 2018, file photo, former Flint Emergency Manager Gerald Ambrose appears in Genesee District Court in Flint, Mich. Prosecutors stunningly dropped all criminal charges against Ambrose, Thursday, June 13, 2019 and seven others in the Flint water scandal and pledged to start the investigation from scratch. (Jake May /The Flint Journal-MLive.com via AP, File)
FILE - In this March 13, 2017, file photo, Robert Scott, data manager for the Michigan Department of Health and Human Services Healthy Homes and Lead Prevention Program, stands in the courtroom of Judge Jennifer J. Manley at the Genesee District Court in Flint, Mich. Prosecutors stunningly dropped all criminal charges against Scott, Thursday, June 13, 2019 and seven others in the Flint water scandal and pledged to start the investigation from scratch. (Jake May/The Flint Journal-MLive.com via AP, File)