A certified nursing assistant from Providence St. Vincent Medical Center has been charged with raping an elderly patient, and investigators believe there could be at least one other victim, according to the Washington County Sheriff's Office.

Adeladilew A. Mekonen, 34, of Portland, is charged with first-degree rape and first-degree unlawful sexual penetration. He was arrested Wednesday and is being held in the Washington County Jail with bail set at $250,000.

The sheriff's office first received a complaint about Mekonen from a 94-year-old woman in June but couldn't substantiate it at the time, said Sgt. Bob Ray, a sheriff's office spokesman. Hospital staff had placed Mekonen on administrative leave after learning of the allegations, Ray said, but he was allowed to return to work after they couldn't be proved.

Last week, an 87-year-old woman came forward with new accusations against Mekonen, Ray said, and the hospital again placed him on leave. Mekonen is charged in that case.

The 87-year-old woman was receiving treatment at St. Vincent for a heart condition, said Greg Kafoury, a Portland attorney representing her.

"Other victims should now feel free to emerge from the shadows," Kafoury said in a statement to The Oregonian/OregonLive.

Ray said Mekonen could face charges tied to the June report after prosecutors review it. He also said that investigators worry there could be additional victims. Mekonen had been working at the hospital since May.

Ray said Mekonen worked as a caregiver for the women, tending to their hygiene.

According to state records, Mekonen was licensed as a certified nursing assistant in February 2015 and has no history of discipline. He graduated from the Caregiver Training Institute in October last year, according to records.

Mekonen was terminated Wednesday following his arrest, said Gary Walker, a Providence spokesman.

In a statement released Thursday afternoon, Nancy Roberts, chief operating officer at Providence St. Vincent, said the hospital continues to work closely with the sheriff's office.

"Caring for patients -- and keeping them safe -- is a privilege and a responsibility that we take very seriously," Roberts said.

Authorities ask anyone with information to contact Detective Robert Rookhuyzen at 503-846-2673.

-- Rebecca Woolington

503-294-4049; @rwoolington

The following clarification was published Sept. 15: A press release from the Washington County Sheriff's Office said Adeladilew A. Mekonen was accused of sex crimes involving two women. Mekonen is charged in Washington County Circuit Court with abusing one woman.