A key witness in the criminal Flint water crisis lawsuit has been found dead, according to authorities in Michigan.

Prosecutors will have to prove criminal cases against employees charged with the Flint water crisis without Karenise Westbrook – a city resident who died last month because of exposure to Legionella bacteria.

Mlive.com reports: During the first day of preliminary examinations for four employees of the Michigan Department of Environmental Quality, special prosecutor Todd Flood outlined a witness roster that included a member of Karenise Westbrook’s family.

Flood had notified attorneys for the defendants that he planned to call Westbrook herself to testify, but she died Dec. 21, before the exams started against DEQ employees Stephen Busch, Michael Prysby, Patrick Cook and former official Liane Shekter-Smith.

Testimony is set to resume in the combined examinations on Monday, Feb. 5, before Genesee District Judge Jennifer Manley.

Westbrook, 52, suffered from kidney disease, according to her death certificate, which does not mention Legionnaires’ disease.

Through a friend of the family, the Westbrooks declined to comment to MLive-The Flint Journal on Karenise Westbrook’s death.

But Flood said she and another Legionnaires’ victim, Robert Skidmore, were both infected with the same Legionella bacteria.

“Mr. Skidmore’s Legionella family and that of Ms. Westbrook, who just recently passed — that bacteria was from the same family …,” Flood told Manley in opening remarks Jan. 8. “The switch (in Flint’s water source) is that which caused the death of these two people.

“The death of the victims in this case — Mr. Skidmore and Ms. Westbrook — they died of complications of Legionella,” Flood said.

Prosecutors claim current and former city and state employees are guilty of various crimes related to the condition of Flint’s water.

Lead levels soared and bacteria thrived after the city’s water source was changed to the Flint River in a cost-saving move in April 2014, a time when the city was being run by emergency managers appointed by Gov. Rick Snyder.

Four individuals have reached plea agreements to resolve their criminal cases while 11 others are fighting the charges in district court.

Including the family representative, Flood has said he plans to call up to two dozen witnesses in making the cases against Busch, Prysby, Cook and Shekter-Smith.

Other remaining potential witnesses include Adam Rosenthal, a DEQ employee who had also been charged criminally but who agreed to cooperate with prosecutors as part of a plea agreement.

Each of the four have claimed they are not guilty of the charges against them but their attorneys have yet to make their cases before Manley.

Flood must prove that the crimes the four are accused of were committed and that the defendants likely committed them to have the cases bound over to Genesee Circuit Court for trial.

The special prosecutor 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.

Other remaining potential witnesses include Adam Rosenthal, a DEQ employee who had also been charged criminally but who agreed to cooperate with prosecutors as part of a plea agreement.