New accounts from Americans who say they were stricken by Havana syndrome are resurfacing after reports that the U.S. government covertly acquired and tested a device believed by some investigators to be linked to the mysterious illness.

Catherine Werner was serving as a foreign security officer in China in 2017 when she awoke repeatedly to a pulsing, humming sound in her apartment.

The Daily Mail reported that each of her episodes was followed by intense head pressure, vomiting, severe headaches and problems with balance.

Her mother later said Werner appeared physically diminished and chronically exhausted.

Werner was one of hundreds of U.S. diplomats, intelligence officers and service members who have reported similar symptoms since cases first emerged in Havana, Cuba, in 2016.

Though initially dismissed by some officials as stress-related, the reported effects have included vertigo, tinnitus, cognitive impairment, and lasting neurological problems.

Living near Werner in China, intelligence officer Mark Lenzi said he heard a recurring noise above his infant son's crib, which he compared to a marble rolling through a metal funnel.

He later developed migraines, dizziness, memory loss and sleep problems. Lenzi described the incident as a targeted attack linked to his classified work analyzing electronic threats.

Other accounts describe severe personal consequences.

One woman said her husband, a U.S. diplomat who traveled to Havana in 2016, underwent dramatic behavioral changes before demanding a divorce and later dying by suicide in 2023.

He left behind five children.

The renewed attention follows reporting that Homeland Security Investigations, using War Department funding, spent more than a year testing a device purchased through an undercover operation.

The device is believed to emit pulsed radiofrequency energy, a theory long cited by some scientists as a possible explanation for Havana syndrome symptoms.

Sources said the device contains Russian components and can fit inside a backpack.

Medical findings have been mixed. Some affected individuals were diagnosed with organic brain injuries despite scans showing no visible structural damage.

Other studies found no measurable differences between patients and control groups, fueling debate within the medical and intelligence communities.

In 2024, a declassified report from the House Permanent Select Committee on Intelligence concluded it was increasingly likely that foreign adversaries were involved and criticized federal agencies for failing to adequately investigate or care for those affected.

For survivors, the disclosure of a potential device has renewed calls for accountability, deeper investigation, and recognition of the injuries they say changed their lives.