The announcement on Monday of charges against Major Evans and two others — Lt. Kashka Meadors and James Ramsey-Guy, a correctional officer — came more than nine months after that inquest, a relatively rare court proceeding in which jurors review evidence relating to a death and decide whether to recommend charges. The four other jail employees who were faulted by jurors at the inquest are not expected to face charges, Mr. Chisholm said, but the investigation was continuing.

Mr. Thomas was arrested in April 2016 and accused of shooting a man and later firing a gun inside a hotel and casino, according to local news reports. A federal lawsuit filed by Mr. Thomas’s estate said he had bipolar disorder and had been prescribed medication by a psychiatrist.

Once he was at the jail in downtown Milwaukee, prosecutors said, Mr. Thomas flooded his cell by stuffing his mattress cover into the toilet. The charging documents said that when Mr. Thomas was moved to another cell, Lieutenant Meadors told Mr. Ramsey-Guy to turn off the water supply to that cell. For the next week, Mr. Thomas did not leave his cell, and was not given any water.

“He was literally punished for the manifestations of his mental illness,” said Erik Heipt, a lawyer for Mr. Thomas’s estate who has filed a federal lawsuit against Milwaukee County and jail officials. “He was not in his right mind. You don’t take someone like that and then punish them by turning off their water.”

After Mr. Thomas’s death, prosecutors said, Major Evans had a guard watch a week’s worth of security video footage of Mr. Thomas’s cell, which showed that the water had never been turned back on. Prosecutors said she did not take steps to preserve that video, and it was eventually recorded over and deleted.