Kenneth Litwack (Daily Pilot / August 30, 2011)

A body matching the description of a missing Newport Beach doctor has been discovered on the grounds of an Arizona clinic he went missing from, authorities said Tuesday.

The body at the Sierra Tucson clinic, located north of Tucson, matches Dr. Kenneth Litwack's description, but the identity of the corpse has yet to be confirmed, said Elias Johnson of the Pinal County Sheriff's Office.

Litwack, 71, an infectious disease specialist with a practice in Newport Beach, checked himself into the clinic Aug. 12 to be treated for pain related to foot neuropathy.

He went missing Aug. 16, his wife, Louise Litwack, has said.

The body, which was in advanced stages of decomposition, was discovered by a clinic staff member about 7:30 a.m. Tuesday. A medical examiner will be needed to identify it, Johnson said.

A ballpoint pen and papers were discovered with the body, although the writing was illegible.

The body was found about 20 yards from where Litwack was spending the majority of his time, Johnson said

It appeared that the unidentified man was seeking shelter, possibly from intense heat and rain, and took off his shirt at some point, Johnson said.

No foul play was suspected in the man's death, but authorities have not ruled that out.

"This is catastrophic," said David Sheffner, Litwack's friend of 40 years.

Sheffner said he felt "bewilderment" at hearing the news that a body was discovered and that it could be Litwack's.

"He was one of the most loved and respected physicians in Newport Beach," Sheffner said. "It's just a tragedy, a catastrophe for so many people."

At the time of Litwack's disappearance, he was without his wallet or watch, though an American Express card was missing from his possessions, Louise Litwack said days after his disappearance.

The official search for Litwack halted on Aug. 23, when an investigation of the area yielded no clues to the doctor's disappearance, Johnson told the Daily Pilot last week.

Some of Litwack's friends went to Tucson to search for him. Family members mobilized a volunteer group to continue the search.

The family offered a $10,000 reward last week for any credible information leading to Litwack's discovery.