The woman, Holly Barlow-Austin, 46, was housed in “deplorable and inhumane conditions of confinement,” deprived of water and denied vital medications, according to the lawsuit, which was filed in the U.S. District Court for the Eastern District of Texas.

Ms. Barlow-Austin was arrested on a violation of the terms of her probation last year and held at the Bi-State Justice Center in Bowie County, Texas, on the border with Arkansas. The jail is operated by LaSalle Corrections, which operates jails in Arizona, Georgia, Louisiana and Texas.

The lawsuit claims that LaSalle failed to monitor and treat Ms. Barlow-Austin’s life-threatening medical needs, and that jail employees failed to “transport her to the hospital until it was too late to save her life.”

“For years, LaSalle has been neglecting and abusing inmates, disregarding their fundamental constitutional rights and engaging in other cruel and inhumane acts and practices,” the lawsuit said.

Ms. Barlow-Austin’s case, it added, “goes to the very heart of everything that’s wrong with the privatization of America’s county jails.”

The lawsuit names jail staff members, LaSalle Corrections and Bowie County as defendants. Sheriff James Prince of Bowie County referred questions about the lawsuit to LaSalle Corrections. Scott Sutterfield, a public affairs officer for LaSalle, declined to comment on the case on Thursday, citing company policy that “prohibits comment during pending litigation.”

Erik Heipt, the lawyer for Ms. Barlow-Austin’s family who filed the lawsuit, has taken on LaSalle before. In 2017, he filed a lawsuit on behalf of the family of Michael Sabbie, a 35-year-old man who died in the same jail in July 2015. That lawsuit claimed employees at the jail showed a “deliberate indifference” to Mr. Sabbie’s health and ignored obvious signs of his declining condition. Lawyers for LaSalle and Mr. Sabbie’s family reached a settlement last year.

The complaint filed on Wednesday argues that in the years leading up to 2019 LaSalle “engaged in a pattern, practice and custom of unconstitutional conduct toward inmates with serious medical needs.” It lists multiple instances, including Mr. Sabbie’s case, as proof that inmates are “systemically denied constitutionally adequate medical care by LaSalle and its agents or employees.

When she entered the jail in April 2019, Ms. Barlow-Austin was managing her H.I.V., taking her medications and still had her eyesight, Mr. Heipt said. By late May, Ms. Barlow-Austin “could no longer walk or stand, and her vision was badly impaired,” the complaint said. Her symptoms included persistent head and neck pain, dizziness and vomiting.

Ms. Barlow-Austin was taken to a hospital on June 11. Mr. Heipt said that by the time she died on June 17, of fungal meningitis, she was blind and gaunt — utterly unrecognizable from the relatively healthy and nourished woman who walked into the jail two months before.

Mr. Heipt shared photos of Ms. Barlow-Austin before her arrest and while in the hospital that show a shocking transformation from a smiling woman in a T-shirt to a hospital patient with a feeding tube and a ventilator.

Video evidence linked in the complaint shows a frail Ms. Barlow-Austin crawling around a medical observation cell.

Mr. Heipt said he watched nearly 2,000 video clips from Ms. Barlow-Austin’s last 48 hours at the jail, each 30 seconds to two minutes long, that he had requested from Bowie County in order to learn what happened.

In the linked clips, Ms. Barlow-Austin can be seen struggling to move, outstretching her hands to feel her away around her cell.

The complaint said that she went long stretches of time without sustenance because she wasn’t able to see food and water in her cell, and that she also was unable to eat properly.

“At several points, she attempts to eat with a plastic spoon,” the lawsuit said. “But because she can’t see, she misses her mouth and spills food on her mat.”

According to the complaint, some guards who were supposed to be monitoring Ms. Barlow-Austin never looked into her cell, while those who did check on her saw her lying on the floor and calling for help but were “deliberately indifferent to her serious medical needs.”

Texas requires that in-custody deaths must be reported. The lawsuit claims that LaSalle tried to circumvent that requirement by releasing Ms. Barlow-Austin from its custody at the hospital “when death was imminent — later claiming that it didn’t have to report her death because she technically wasn’t ‘in-custody’ when she died.”

Another LaSalle-operated facility, the Irwin County Detention Center in Ocilla, Ga., made headlines this week after allegations surfaced that immigrant women detained there underwent gynecological procedures without fully understanding or consenting to them.

A 2018 investigation by The Dallas Morning News found that thousands of untrained jailers were working in Texas under a loophole that allows jails to employ temporary guards for up to 12 months. At that time, the newspaper found that LaSalle had “hired more than 370 jailers with temporary licenses at less than a dozen facilities around the state since 2017.”

Mr. Heipt said untrained jailers and understaffed jails played big roles in the problems at facilities run by LaSalle, but he expressed skepticism that the company was capable of change.

If they made the changes needed to make the jail safe, “they would no longer profit on that contract,” he said.