Updated

Malfunctioning bugging devices planted by the Cuban government may be to blame for the illnesses that struck 24 U.S. Embassy employees last year in Havana, according to The Daily Beast.

The theory about what could have caused the so-called “sonic attacks” arose from a study by three computer scientists at the University of Michigan, who analyzed an Associated Press video of a high-pitched sound that an embassy victim had recorded.

Some of the victims reported hearing the sound before falling ill. The illnesses ranged from dizziness and headaches to hearing losses and cognitive impairment. U.S. officials have said they believe the Cuban government either launched sonic attacks, or was aware of them if another party was involved.

The Cuban government has denied involvement.

The matter grew so grave that the U.S. State Department recalled 21 employees from the embassy, and recently said it would not restore full-staffing because of a lack of trust in Cuban authorities and concern for the health of its workers.

But the theory by the Michigan computer scientists holds that the Cuban government may have placed bugging devices whose transmissions got tangled, creating the tone that some victims reported hearing.

“It doesn’t prove that this is what happened in Cuba,” said Michigan professor Kevin Fu, a co-author of the report on the study, to The Daily Beast. “It’s a correlation. But to us, it seems like a strong correlation.”

“It’s an alternative hypothesis to the sonic-weapon theory, of someone trying to cause harm. It’s a theory that seems a little more practical in that it could be bad engineering. It seems like a reasonable hypothesis.”

Complicating matters, the victims were not all in one place when they heard the sounds and fell ill. Some were at the embassy, others were in hotels or homes.

Doctors who have examined the victims are perplexed.

Some of the doctors attributed the cause to a “novel mechanism” that triggered neurological damage.

The medical journal JAMA published a report on the Cuba situation said a high-intensity ultrasound could cause heating and damage of brain tissue. The report was inconclusive, however.