Arizona authorities on Friday confirmed that a decomposed body found at a medical clinic near Tucson was that of a missing Newport Beach physician.

The corpse of Dr. Kenneth Litwack, 71, of Corona del Mar was identified by family members and with the help of evidence found with his body on Sierra Tucson's grounds, said Elias Johnson, public information officer for the Pinal County Sheriff's Office.

"It's tough," said Louise Litwack, who was married to Litwack for 46 years. "It's such an incredible loss. We've really learned nothing new. We're just left with dealing with it."

The Sierra Tucson clinic contains 30 to 40 acres. Litwack's body was found in a remote area of it filled with thick brush, Johnson said.

"It's a tough hike if you're not on a trail," he said. "We imagine the elements were pretty hostile."

A Sierra Tucson staff member found the decaying body at about 7:30 a.m. Tuesday, Johnson said.

Along with the body, authorities found an inactive American Express card, clinic admission paperwork and a ballpoint pen, although there was no writing was visible on the papers, according to authorities.

Pinal County sheriffs did not search the clinic's grounds because staff had assured them that they checked the area when Litwack disappeared, Johnson said.

"We couldn't locate him because he never went outside the facility," Johnson said. "He never left."

Litwack was an infectious disease specialist who practiced near Hoag Hospital in Newport Beach. He was admitted to Sierra Tucson on Aug. 12 to be treated for foot neuropathy — or damage to the nervous system.

Funeral services for Litwack will take place at noon Tuesday at Congregation Shir Ha-Ma'alot, 3652 Michelson Drive, Irvine.