The staff of the Milwaukee County Jail is being blamed by prosecutors for allowing a 38-year-old inmate with bipolar disorder to sit in a solitary confinement cell for seven days and die of dehydration, according to an inquest to determine whether personnel there should face criminal charges.

But the commander of the jail, which is run by controversial Sheriff David Clarke, has become the focus of the probe because of the disappearance of surveillance video linked to the case, according to USA Today.

Major Nancy Evans was questioned for 90 minutes about the April 24, 2016 death of Terill Thomas on Tuesday, the second day of the inquest. A jury is hearing testimony and will determine if probable cause exists to file charges over his death.

Evans told prosecutors that she had no explanation for why the surveillance video had disappeared. According to the Journal-Sentinel, the tape would have provided evidence as to who shut off Thomas’ water supply, but did not let other corrections officers know.

Police detectives asked her in a questionnaire they sent her last summer if there was any documentation showing whether the water was turned off the whole time or if it was turned on intermittently, the Associated Press reported. The document Evans signed off on answered that “there is no documentation indicating this.” However, prosecutors say Evans was aware of the tape and what it showed by then.

Thomas was said to have been having a mental breakdown on April 14, 2016 when he was arrested after a shooting and also for firing a gun in a casino. He was placed in a special needs unit because of his bipolar disorder condition and was not taking medication. But he was transferred to solitary confinement three days later, where he tore up a mattress and stuffed it in a toilet, which flooded his cell.

But when he arrived in solitary, an officer turned off the water in Thomas cell, the footage on a surveillance video showed. “This order to shut off Mr. Thomas’ water was highly irregular and contrary to standard operating procedure in the jail,” Assistant District Attorney Kurt Benkley said to jurors. While he was locked in his cell, Thomas consistently banged on the door and shouted. “It will become apparent he was unable to tell people about his basic needs,” Benkley said.

Capt. George Gold testified that his jail commander, Nancy Lee Evans, directed him to review the video the day after Thomas died and report to her what he saw. Gold said after the guard turned off the water he didn’t see anyone turn it back on.

“They lock him up and then they never let him out until they take him out dead, correct?” Bentley asked Gold, who agreed, according to the Associated Press.

Prosecutors say he was fed the meat substitute NutraLoaf, which did not come with water or milk, USA Today reported. Thomas’ three sons have filed a federal civil suit in March against Milwaukee County Sheriff Clarke and the staff saying he was subject to “a form of torture” while being held.