A fourth person has died in connection with the Legionnaires’ outbreak on the Upper East Side, city Health Commissioner Dr. Alister Martin said early Monday evening.

At this time, we believe any source of exposure has likely been eliminated. We have not seen anyone with new symptoms in over a week. We are focused on inspecting every cooling tower that tested positive and enforcing our laws to their fullest extent.

— Dr. Alister Martin (@NYCHealthCommr) July 20, 2026

As of Monday, there had been 76 reported cases of Legionnaires’ disease associated with the outbreak, according to the Health Department’s website. A first death in the outbreak was announced on Friday, a second death was announced on Saturday and a third death was announced on Sunday.

The Health Department’s website indicates that 53 people have been discharged from the hospital after being treated.

“At this time, we believe any source of exposure has likely been eliminated. We have not seen anyone with new symptoms in over a week,” Health Commissioner Alister Martin wrote on social media.

“We are focused on inspecting every cooling tower that tested positive and enforcing our laws to their fullest extent,” Martin added.

Officials say no new cases have been diagnosed since July 15, and no one has developed symptoms in more than a week.

“We believe that we have now eliminated the source of exposure," Mayor Zohran Mamdani said.

All 76 buildings that were ordered to clean and disinfect their cooling towers have done so, the department said.

Officials believe one, or possibly more, of those towers released contaminated mists into the surrounding neighborhood.

“We’re waiting for the investigation to be completed to identify the responsible cooling tower owner," Ronald Katter, an attorney, said.

Katter represents the widow of an 88-year-old military veteran who died after spending two weeks in the ICU. His identity was not yet made public.

The man's own apartment building tested negative and was not among the buildings ordered to disinfect.

“He was suffering from pneumonia, organ failure, he was intubated, on a respirator," Katter said.

Katter is also representing another patient who lives outside the affected area, but regularly visited the Upper East Side.

He says identifying the source will determine which building owner could face claims for pain and suffering and wrongful death.

“They’re looking to be made whole from the suffering they’ve experienced," Katter said.