Legal advocates and public health experts say Mayor Bill de Blasio isn't moving fast enough to release vulnerable individuals detained at the city's jails, amid mounting evidence that COVID-19 is already spreading on Rikers Island.

Facing calls to address inadequate safety measures in local jails, the mayor said on Wednesday that he would move swiftly to grant the release of certain individuals in the city's custody most at risk from infection of the novel coronavirus.

“In the next 48 hours, we will identify any inmates who need to be brought out because of either their own health conditions — if they have any pre-existing conditions, etc. — or because the charges were minor and we think it’s appropriate to bring them out in this context," he promised.

Forty-eight hours later, the city has only identified 40 detainees who meet that criteria — out of roughly 7,000 men and women in the city's jails. Neither the Mayor's Office nor the Department of Correction responded to inquiries about whether any detainees have been released.

On Friday, the Legal Aid Society filed a lawsuit on behalf of 116 individuals incarcerated on parole violations or awaiting trial who are at substantial risk — ranging from a 76-year-old with underlying medical issues to a 19-year-old with asthma.

As it stands, there are more than 700 individuals jailed for technical parole violations, such as staying out past curfew, missing an appointment, or even "fraternizing" with their girlfriends.

Keeping such low-risk individuals behind bars, the suit alleges, represents "deliberate indifference" on the part of the mayor to an "unconscionable and entirely preventable risk of harm" posed by the already-spreading virus.

A Department of Correction investigator, who was said to have "limited contact" with those in custody, was pronounced dead from COVID-19 this past weekend. One Rikers detainee and one Department of Correction officer have since tested positive for the virus.

Speaking with Brian Lehrer on Friday morning, the mayor said the city would begin evaluating additional cases once it received approval from local district attorneys — and, depending on the charges, the state — for the first 40 detainees identified for possible release.

A spokesperson for Brooklyn District Attorney Eric Gonzlez told Gothamist they have approved the release of ten individuals, and would begin reviewing cases on their own. The office has consented to release anyone who owes less than a year on a drug misdemeanor charge, and those who have 90 days left on a jail sentence, with the exception of sex crimes and domestic violence cases.

Inquiries to the city's other four district attorneys were not immediately returned.

Meanwhile, the mayor is now downplaying the current risk to those incarcerated, claiming on Friday that, since the city's jail population has declined under his tenure, there's "actually a lot of space available on Rikers...to socially distance someone."

That assertion runs counter to dire warnings posed by health professionals, including both the former and current chief medical officers on Rikers Island.

In a thread on Twitter this week, the Correctional Health Services head doctor Ross Macdonald said it was not conceivable to protect the most vulnerable detainees in city jails from the rapid transmission of the virus.

"We cannot change the fundamental nature of jail," he wrote. "We cannot socially distance dozens of elderly men living in a dorm, sharing a bathroom. Think of a cruise ship recklessly boarding more passengers each day,”

“A storm is coming and I know what I’ll be doing when it claims my first patient. What will you be doing? What will you have done? We have told you who is at risk. Please let as many out as you possibly can.”