FLINT, MI -- Special Flint water prosecutor Todd Flood plans to lay out the criminal cases against four current and former Michigan Department of Environmental Quality employees with 24 witnesses, including four who made plea deals previously.

Flood called the first of those two dozen planned witnesses Monday, Jan. 8, in a Genesee District Court preliminary examinations for Liane Shekter-Smith, former director of the Office of Drinking Water and Municipal Assistance; Stephen Busch, a district supervisor; Michael Prysby, a district engineer; and Patrick Cook, a community drinking water specialist.

Plans for LeeAnne Walters, a Flint mother whose home registered shocking levels of lead during the water crisis, to testify Monday were put on hold because of a lack of time.

William Brown, a former DEQ engineer and deputy division chief at the agency, was the first to testify Monday, a process that moved slowly as attorneys for all four defendants raised objections and some cross examined the retiree.

Flood told Judge Jennifer Manley that he expects to need at least nine days to bring two dozens witnesses before her.

Among them:

Mike Glasgow and Daughtery Johnson, former Flint utilities officials, each of whom accepted plea agreements to avoid prosecution by Flood. Glasgow warned state regulators in an email of potential problems if they allowed the Flint water plant to begin treating Flint River water in April 2014.

Former DEQ Director Dan Wyant, who resigned his position in December 2015 after a state task force laid responsibility for the water crisis at the feet of the department.

Valerie Brader, former deputy legal counsel to Snyder, who called the city's water problems "an urgent matter to fix" before problems were acknowledged by city and state officials.

Relatives of two victims of a Legionaires' disesase outbreak in the Flint area while the Flint River was being used as the city's water source.

Laura Sullivan, a Kettering University professor and member of Snyder's Flint Water Interagency Coordinating Committee. Sullivan attended a July 2015 meeting with Dennis Muchmore, the governor's former chief of staff, and others about problems with Flint water.

The Rev. Allen Overton, representative of the Concerned Pastors for Social Action. The group was a plaintiff in a lawsuit against the city and state that resulted in a settlement regarding replacement of lead service lines and bottled water distribution.

John O'Brien, division director in the Genesee County Drain Commissioner's Office. Flood said O'Brien told investigators he called Busch, asking why the Flint water plant was allowed to be put into service after decades without producing drinking water and was told "because of pressure from above."

David Jansen, senior assistant director at the county drain office.

Jim Sygo, former deputy director of the DEQ, who has testified in the prosecution of Dr. Eden Wells, the state's chief medical executive. Sygo told Michigan State Police in March 2016 that the water crisis was "overplayed" and "more created than anything else" -- possibly by people with ulterior motives.. He was one of several DEQ employees who defended colleagues Busch and Prysby during the MSP investigation.

Shawn McElmurry, a Wayne State University professor who has led efforts to discover a connection between Flint water and the Legionnaires' outbreak. McElmurry has testified in the preliminary examinations of Wells and Nick Lyon, director of the Department of Health and Human Services.

Miguel Del Toral, the U.S. Environmental Protection Agency official who warned the federal government about about toxic lead in Flint's drinking water and a leading expert on water treatment, corrosion and the federal Lead and Copper Rule. Del Toral wrote an interim report on high levels of lead in Flint water on June 24, 2015, months after other EPA officials had warned the MDEQ

Corinne Miller, a retired state epidemiologist, who accepted a plea deal with prosecutors, and who testified during Lyon's preliminary exam, that there was a special sensitivity among employees at the Michigan Department of Health and Human Services about sharing information about Flint water as early as January 2015.

Adam Rosenthal, a water quality analyst for the DEQ, who pleaded no contest Dec. 20, to a public records charge, a one-year misdemeanor that's expected to be dismissed provided he cooperates in other prosecutions.

Brown testified Monday that the city was dealing with a "different quality source" of water when it stopped paying for pre-treated water from the Detroit Water and Sewerage Department and attempted to use the Flint River instead.

He called the river water "substandard to Lake Huron water" and said the switch in water sources was "somewhat unique."

Under questioning from Mark Kriger, an attorney for Busch, Brown said the DEQ cannot mandate that a municpality use a particular water source when its water meets state and federal standards.

Although city and state officials maintained they met Lead and Copper standards, the city disregarded federal rules that required it seek out high-risk homes for testing, such as those with lead service lines, according to records obtained by The Flint Journal-MLive in 2015.

The EPA requires that water sampling be done at "high-risk" locations whenever possible to better ensure that high levels of lead or copper are detected as soon as possible -- before problems are allowed to fester and spread.

Flood has said he plans to pursue involuntary manslaughter charges against two of the four DEQ defendants -- Busch, 41, and Shekter-Smith, 57.

Prysby, 54, is charged with two counts each of misconduct in office, tampering with evidence and violation of the Safe Drinking Water Act.

Cook, 54, is charged with willful neglect of duty, misconduct in office and conspiracy.

Busch also faces six additional criminal charges, and Shekter-Smith is also charged with misconduct in office and willful neglect of duty.