(Updates with reports of charges against former health director)
DETROIT, Jan 14 (Reuters) - Michigan's former health director was charged Thursday with involuntary manslaughter as part of a years-long criminal investigation into the crisis surrounding lead contamination of the drinking water system serving the city of Flint.
Nick Lyon pleaded not guilty to the charges, which were linked to the deaths of nine people, at his arraignment in a Gennessee County court on Thursday, according to media reports.
Former Governor Rick Snyder and Howard Croft, Flint's former public works director, were also arraigned, the reports said.
Michigan's attorney general and a team of prosecutors are due to unveil the full findings of their investigation into the Flint water crisis later on Thursday morning.
Snyder was charged on Wednesday with two misdemeanor counts of willful neglect of duty for his role in a debacle that afflicted the predominantly African-American city and became emblematic of racial inequality in the United States.
Flint's troubles began in 2014 after the city switched its water supply to the Flint River from Lake Huron to cut costs. Corrosive river water caused lead to leach from pipes, tainting the drinking water and causing an outbreak of Legionnaires' disease.
The contamination also prompted several lawsuits from parents who said their children were showing dangerously high blood levels of lead, which can cause development disorders. Lead can be toxic and children are especially vulnerable.
A civil settlement of more than $600 million was reached with victims of the water crisis in August 2020 and is awaiting court approval.
The date of the misdemeanor offense in charging documents filed against Snyder and posted online was listed as April 25, 2014, the day the city switched water systems. Each count carries a maximum penalty of a year in jail and a $1,000 fine.
The Detroit News has reported that as many as 10 people in all faced charges stemming from the water crisis, including some former members of Snyder's administration.
Snyder, a Republican who has been out of office for two years, was governor when the city of some 100,000 residents was under the control of a state-appointed manager in 2014. He was succeeded by Governor Gretchen Whitmer, a Democrat.
The former Wayne County prosecutor appointed in 2016 to lead the state's investigation of the matter said then that he was looking to determine whether any officials who signed off on the change in the water system had acted criminally.
On Wednesday, the office of the state attorney general, Dana Nessel, also a Democrat, said the findings of that inquiry would be announced at a news conference on Thursday, along with Michigan Solicitor General Fadwa Hammoud and Wayne County Prosecutor Kym Worthy.
Snyder has repeatedly apologized for the state's poor handling of the crisis, but his lawyer, Brian Lennon, has said any prosecution of the former governor would be politically motivated.
"It is outrageous to think any criminal charges would be filed against Governor Snyder. Any charges would be meritless," Snyder said in a statement the day before the case was filed.
Nessel's office declined to comment on the case ahead of Thursday's news conference. (Reporting by Daniel Trotta, Brendan O'Brien, Ben Klayman and Nathan Layne; additional reporting and writing by Steve Gorman; editing by Jonathan Oatis)