Vehicles drive through downtown Flint Wednesday. Some Flint residents impacted by months of lead-tainted water are looking past charges brought against former Gov. Rick Snyder and others in his administration to healing physical and emotional damages left by the crisis. (AP photo)

FLINT — Two former Michigan health officials were charged Thursday with involuntary manslaughter in the deaths of nine people who got Legionnaires’ disease during the Flint water crisis, as prosecutors revisiting how the city’s water system was contaminated with lead and bacteria also hammered a key adviser to ex-Gov. Rick Snyder with extortion and perjury crimes.

Snyder joined a parade of former state and local officials pleading not guilty in Genesee County courts. He’s facing misdemeanor charges of willful neglect of duty in Flint in a case that was filed Wednesday night, the first governor or former governor in Michigan’s 184-year history to face charges related to time in that office.

Details behind the charges weren’t disclosed in court. Michigan Attorney General Dana Nessel and prosecutors planned to hold a late morning news conference.

Wearing a mask, Snyder, 62, said little during his brief hearing, which was conducted by video. He replied, “Yes, your honor,” when asked if he was living in Michigan. A conviction carries up to a year in jail and a $1,000 fine upon conviction.

Defense attorney Brian Lennon called the case a “travesty.”

“These unjustified allegations do nothing to resolve a painful chapter in the history of our state,” Lennon said in a written statement. “Today’s actions merely perpetrate an outrageous political persecution.”

Former state health director Nick Lyon and former state medical executive Eden Wells were each charged with involuntary manslaughter.

Snyder, a Republican, was governor from 2011 through 2018. The former computer executive pitched himself as a problem-solving “nerd” who eschewed partisan politics and favored online dashboards to show performance in government. Flint turned out to be the worst chapter of his two terms due to a series of catastrophic decisions that will affect residents for years.

The date of Snyder’s alleged crimes in Flint is listed as April 25, 2014, when a Snyder-appointed emergency manager, Darnell Earley, who was running the struggling, majority Black city carried out a money-saving decision to use the Flint River for water while a pipeline from Lake Huron was under construction.

The corrosive water, however, was not treated properly and released lead from old plumbing into homes.

Despite desperate pleas from residents holding jugs of discolored, skunky water, the Snyder administration took no significant action until a doctor reported elevated lead levels in children about 18 months later.

Lead can damage the brain and nervous system and cause learning and behavior problems. Flint’s woes were highlighted as an example of environmental injustice and racism.

Prosecutors charged Earley with misconduct in office. Rich Baird, a friend and close adviser to Snyder, was charged with extortion, perjury and obstruction of justice. Jarrod Agen, who was communications director before going to work for Vice President Mike Pence, was charged with perjury. He subsequently left government for a job with a defense contractor.

Authorities counted at least 90 cases of Legionnaires’ disease in Genesee County during the water switch, including 12 deaths. Some experts found there was not enough chlorine in Flint’s water-treatment system to control legionella bacteria, which can trigger a severe form of pneumonia when spread through misting and cooling systems.