George Washington University has stopped accepting donated bodies at its medical school because it lost track of the identities of as many as 50 cadavers, making it impossible to return remains to families as promised.

The university had operated a “willed body donor program” for people who opted to donate their bodies to the medical school. The school uses between 30 and 40 cadavers for classroom instruction each year, and the university maintains a list of hundreds who have arranged to donate their bodies.

Cadavers are a focal point of anatomy classes for medical students and are generally in use for up to two years before they are cremated; remains are either returned to families or buried by the university at Mount Olivet Cemetery in Northeast Washington.

But senior officials at the medical school received a complaint in the fall from an employee about “irregularities” in the program, according to Anne Banner, a spokeswoman for the medical school.

[Cadavers provide an intimate education as medical students’ first patients]

The school launched an internal investigation that led to the departure of the program manager and a suspension of further donations.

“The program’s operating procedures were inconsistently followed and there was a lack of appropriate oversight of the program,” Banner wrote in an email. She would not say whether the previous manager had been fired or had resigned.

The university began notifying families this week.

“I was shocked,” said Eileen Kostaris, who had been waiting for George Washington University to return the remains of her 92-year-old grandmother so she could hold a memorial service at her grandmother’s church in Rockville. “I don’t even know what to say. I just couldn’t believe it. It’s horrible.”

Kostaris said she was contacted by Christina Puchalski, a physician and instructor at the medical school who also directs a university program designed to integrate spirituality into medical education.

“She said the remains were either mislabeled or not labeled at all,” Kostaris said. “It’s crazy. How does this happen?”

Kostaris’s grandmother, who died last spring, had arranged years ago to donate her body to the medical school, just as Kostaris’s late grandfather had done. Neither had a medical background but both wanted to do something to benefit society, she said.

“My grandmother was a lifelong Washingtonian — she lived in Georgetown for the most part and then Foggy Bottom, and she and my grandfather had both chosen to do this,” she said.

Banner could not say how many cadavers the medical school has, or how many people have arranged to donate their bodies. Donors will have to find another program. She also could not say how long George Washington University has operated the program.

Banner said that she does not think the donation program will resume but that current students will not be affected because the medical school has enough cadavers from earlier donations and on loan from other institutions to meet its needs.

In a statement released Friday, medical school dean Jeffrey Akman apologized.

“As the dean and as a former medical student whose education benefitted greatly from the altruism of a body donor, I extend my deepest and most sincere apologies to all of the affected families and the entire [School of Medicine and Health Sciences] community,” he said in the statement.

[George Washington was the nation’s only med school on probation in 2008]

Kostaris, who said she had a special bond with her grandmother, said the mix-up at George Washington has added another layer of emotion to her grief, which is still fresh.

“I am angry, but what’s done is done,” Kostaris said. “I don’t want to be angry over it. That’s just a wasted emotion. There’s nothing I can do. It’s totally out of my control.”

University officials say they will try to make identifications through DNA testing of relatives. Kostaris has agreed to the testing, though she said she was cautioned by Puchalski that “there are no guarantees.”

Even if university officials tell her they’ve been able to match the DNA, Kostaris said her faith has been so shaken, she’ll always be unsure.

“My 12-year-old son said to me, ‘Mom, you’ll never know — they could just hand you a bag of rocks and say here it is and you’ll never know for sure,’” Kostaris said. “And he’s right.”

On its website, the medical school recommends that ­D.C.-area residents who wish to donate their bodies to scientific research consider Georgetown or Howard universities or consider donating their tissues for transplantation to living patients.