A beloved UAB doctor has died after he suffered a severe head injury while on vacation in Mexico.

William Thomas O'Byrne III, 54, was pronounced dead Wednesday at UAB Hospital where he had been on life support after he was flown back to the United States. O'Byrne was an anesthesiologist who specialized in critical care.

The Jefferson County Coroner's Office confirmed they were notified of a William O'Byrne's death at UAB Hospital following a reported assault in Mexico. Because the incident took place outside of Jefferson County, the coroner's office here is not involved per state law.

Details about what led to the injury aren't clear. Friends say O'Byrne took a vacation with friends to Puerto Vallarta when he was severely beaten and left for dead in a ditch. His friends found him at a hospital where he was hooked up to a ventilator. He was later flown back to Alabama.

That account hasn't been confirmed by American authorities. Law enforcement officials in Birmingham said they haven't been made aware of the incident. If any crime happened, the law enforcement jurisdiction also would be in Mexico. Inquiries to the U.S. Department of State were not immediately answered.

A spokesman at the U.S. Embassy in Mexico City said they are aware of the case, and are working to gather information for release. On Friday, they released this statement to AL.com: "We are aware of reports regarding a U.S. citizen injured in Puerto Vallarta, Mexico. Out of respect for the family, we decline further comment at this time."

O'Byrne, a Blount County native, graduated from the University of South Alabama College of Medicine in 1997. He most recently worked UAB Hospital, where he was also an associate professor.

UAB officials provided only this statement: "At the request of the family, we have been asked not to release any information."

Dr. Jason Hall, an anesthesiology resident at Duke, said O'Byrne was a special man.

"Like he was to so many medical students and residents before me, he was my mentor and friend,'' Hall said. "He was a gifted physician trained both in medicine and anesthesiology with fellowship training in critical care. He showed kindness and genuine concern for his patients above and beyond that of other physicians."

Hall said O'Byrne always demonstrated the utmost respect for his colleagues and co-workers.

"He was loved by many wherever he went, be it UAB, New Mexico, or Vanderbilt,'' Hall said. "His passing is a terrible loss for the medical community, and he will be truly missed. His friendship and advice has comforted and motivated me throughout my medical training, and I can only hope to live up to the example he set for all physicians."