His patients called him Dr. Akoda.

As an obstetrician-gynecologist at Prince George's Hospital Center, women trusted him to care for them in some of their most vulnerable moments. He gave them their annual checkups, treated their ailments and delivered their babies.

But their faith in the doctor who had practiced for years at the hospital just outside Washington quickly vanished after federal authorities announced that Akoda was not the man he said he was.

Akoda was actually Oluwafemi Charles Igberase, who used a fake Social Security number to obtain his medical license in Maryland. A federal investigation revealed his true identity and that he had been using stolen Social Security numbers to advance his medical career and obtain professional certifications for at least 25 years.

"I'm shook because of this," said one of Igberase's former patients, who said she feels betrayed. "This makes me even scared to go to the hospital. He could have put my son's life and my life in danger."

The woman, who spoke on the condition of anonymity because of the sensitive nature of her claims, is one of more than 100 patients who are part of a class-action lawsuit against Prince George's Hospital Center. The women said the hospital failed to perform a proper background check on Igberase and allowed an impostor to practice medicine at the facility for five years.

Igberase was removed from the hospital in 2016 after he was indicted on federal fraud charges. In a statement to The Washington Post, the hospital said Igberase's conduct failed to meet the facility's expectations regarding "sound moral character" but that his credentials and experience appeared valid.

"We are exploring many aspects of this case, researching records, and evaluating processes and procedures upon which we rely to validate information," the statement from Prince George's Hospital Center said. "Several highly reliable agencies validated his credentials including the states in which he held medical licenses."

Igberase, whose attorney did not respond to a request for comment, pleaded guilty in November 2016 to a federal fraud charge. He admitted to using four Social Security numbers under three names to apply for medical certifications, federal education loans for his children and his license to practice medicine. Authorities also found that Igberase had not only forged or altered his medical diploma, medical transcripts and letters of recommendation but also had a false passport, visa, birth certificate and immigration documents.

Jonathan Schochor, an attorney representing the plaintiffs in the class-action lawsuit, said the former patients were "shocked and betrayed" to learn of the fraud conviction. Patients in hospitals where births, surgeries, diagnoses and treatments occur expect a private safe haven, Schochor said. But the revelations that Igberase wasn't who he said he was created a breach of trust.

"They've all said to us that they're worried for themselves and they're worried for their children," Schochor said. "Has he performed cesareans or surgeries that he shouldn't have? Has he performed or not performed tests that he shouldn't have?"

Schochor said he doesn't understand how Prince George's Hospital Center missed so many red flags concerning Igberase.

Igberase came to the United States in October 1991 on a nonimmigrant visa, according to federal court documents. He obtained fraudulent Social Security numbers and claimed someone else's identity a month later, as well as twice more, in 1995 and 1998.

In 1992 and 1993, he failed basic exams for the Foreign Medical Graduate Certification, required for people from other countries to enter medical education programs in the United States, the lawsuit says. He eventually met the requirements, but in 1995, the certifications were revoked because the committee discovered he had used different names and dates of birth to apply for the credentials, the lawsuit says.

About five years later, a medical center in New Jersey removed him from its residency program after learning he had used a false date of birth and Social Security number to apply as "Akoda," the lawsuit says, and in 2012, the federal government rejected his application for a Medicare claim after saying it had received someone else's Social Security number for the application.

Schochor said a thorough background check would have uncovered the discrepancies in the doctor's history, names and Social Security numbers.

"How in the dickens does a hospital permit that kind of a person to go ahead and practice at that institution as a credentialed OB/GYN for years?" Schochor said.

There are multiple class-action lawsuits in the case, including the first one filed by attorney Cory Zajdel, who is working with attorneys David Ellin and Peter Angelos to represent more than 180 patients separate from Schochor's clients.

In a motion to dismiss claims, attorneys for the hospital's parent company, Dimensions Health Corp., wrote in court filings that although the doctor who treated patients who are suing was not really named Akoda, he still was licensed to practice medicine in Maryland.

"As Shakespeare wrote over 400 years ago, 'What's in a name? That which we call a rose by any other word would smell as sweet,' " the lawyers for Dimensions wrote. "Whether the patients knew him as 'Akoda' or 'Igberase,' both names denote the exact same person, and that person was a licensed physician who was experienced and competent in the practice of obstetrics and gynecology."

According to the hospital, "Akoda" was certified by the Educational Commission for Foreign Medical Graduates; "applied to, was accepted, and successfully completed a four-year residency program at Howard University from 2007-2011"; "performed satisfactorily" on exams administered annually and nationally to obstetrics and gynecology residents; and had obtained medical licenses from Maryland and Virginia, which remained in good standing through the time of his work at the hospital.

Prince George's Hospital Center said he was also board certified from the American Board of Obstetrics and Gynecology and was named "Resident of the Year" in his final year at Howard University.

"We acknowledge the concerns expressed by some of his former patients," the hospital said. "However, it remains a fact that Dr. Akoda was a trained, licensed, and qualified obstetrician and gynecologist during the entire period he had privileges to practice at our facility."

But the former patients said that if they can't trust that their doctors are who they say they are, they can't trust that they were getting the right medical care for themselves and their families.

The woman whose child was delivered by Igberase five years ago said she discovered he was a fraud after her friend told her to turn on the news one day and she saw Igberase's face flashing on the television in a piece about his federal conviction — and immediately broke into tears.

The woman, who had complications during her delivery and a very difficult labor, said she immediately began to question whether she received appropriate medical care, and she worried about her and her child's health.

"I trusted him," the woman said in an interview. "This is something where you're dealing with lives, you're dealing with babies, you're dealing with personal areas."

Now, she said, "I don't know who is this man that touched me in a private area and delivered my child."

(This file has been updated to note that there are multiple class-action lawsuits in the case)