In the family’s correspondence, the code name for Aribert Heim was Gretl, the little girl who got lost in the woods with her brother Hansel. When Rüdiger sat down to inform his father about what was happening, he spun his own fairytale modeled on the Brothers Grimm.

When Gretl awoke one morning it had just turned the fifth week of the New Year and she was not feeling particularly well. She decided to buy herself a Spiegel. The old one was already too old and one couldn’t recognize anything in it anymore. But no sooner had she bought the new Spiegel then she went home and looked inside. It shocked her terribly for what was inside did not please her at all. Her entire misery was mirrored in her face once more. She suddenly had a vision that came out of this Spiegel. If one day, all of a sudden, the poor girl could no longer receive bread and if water was no longer brought up to her room, well then she would inevitably starve and die of thirst or else she would have to go out into the forest to provide for herself. But the forest was teeming with wolves and they would most certainly tear her to pieces. There was still Rainer, however, and he could certainly help her. She simply had to make contact with him and he would give her counsel. Oh that would all be terrible, thought Gretl, and sat down to try to recover from the scare.

In plain language, Rüdiger wanted his father to acquire a copy of Der Spiegel. He had to talk to his attorney, Fritz Steinacker, “Rainer” in code. His livelihood, and possibly his life, depended on it.

***

When Rüdiger Heim returned to Egypt to visit his father again, the ever-practical Heim asked only for razorblades and Faber-Castell pencils. Rüdiger brought exactly what he was told. He was not, however, fully prepared for what awaited him upon their reunion. The two men could no longer avoid the topic of his father’s wartime service and fugitive status as they had during his first visit.

For hours each day, Rüdiger had to relive his father’s months at the Mauthausen concentration camp and try to maintain belief in his innocence. Heim defined the terms of the discussion. They did not talk about the condition of the inmates brought to the infirmary from the stone quarry. They did not discuss how the patients were treated. Heim tried to reinforce the point that he would sooner not have been working at Mauthausen. “That was something he expressed to me unequivocally: That he did everything he could to get out of this concentration camp as quickly as possible,” Rüdiger said. Each day, the son dutifully walked from the Scarabee Hotel downtown to listen to hours of lectures on the crimes his father was accused of committing.

The visit was much more of a shock than his previous trip to Cairo and not just because of the civil case against his father. The city was busier, more crowded. Downtown had fallen into disrepair. The country had become more religious and the girls in miniskirts were gone. Women in modest clothes and headscarves had replaced them. The religious revival was in part due to the rising tide of migrants from more observant villages. But many young people had simply fled their stagnant economy and found jobs thanks to the oil boom in Saudi Arabia and other Gulf states. When they returned with petro-dollars in their pockets, they often practiced a stricter, sometimes Wahhabi interpretation of Islam. Rüdiger realized that along with changing his name to Tarek Hussein Farid, his father had also converted to Islam. But this was a subject they did not discuss.

Heim talked a great deal about when he was actually at Mauthausen. Witnesses described him working at the camp in 1942 when in reality he left in 1941. Spiegel magazine said he had committed his crimes between a special room for shooting prisoners in the neck and the gas chamber, when neither existed in 1941.

He spoke very specifically about the charge that he had murdered an older inmate. Heim explained that the patient wanted an operation for his hernia but the doctor determined once he began that the man had not only a hernia but also cancer. That was the reason he had taken the intestines out of the abdomen. “If someone comes in at that point, who has never seen an operation, he would say, ‘Look, he’s tearing out all his intestines,’” he told his son. Rüdiger asked him why he was even there in the first place. His father explained how in order for him to finish his studies, it was necessary for him to enlist in the Waffen-SS. He did not realize that would mean service at concentration camps.

Eventually Rüdiger could not take it anymore. “The subject isn’t pretty, and naturally your head is smoking after two, three hours.” His father suggested he spend a week on the Red Sea to recuperate. Rüdiger traveled to Hurghada, where he stayed in a small bungalow on stilts at the edge of the water. When he was not going for walks or swimming, he was reading about Egypt, which he had not done on his first visit. He enjoyed looking out across the water at the Sinai Peninsula.

After several weeks it was time to say goodbye. Rüdiger left still believing his father was innocent of most of the charges against him. Throughout their discussions his father had remained “factual and sober,” Rüdiger said, “not emotional.” Rüdiger remained uncertain about what had taken place at Mauthausen. He did not believe that his father was wholly blameless after working in a concentration camp. But he also could not believe that Aribert Heim was guilty of the atrocities he was alleged to have committed.

***

Rüdiger returned to Egypt in July 1992 for what he expected to be his last visit. Father and son spoke regularly, with Rüdiger calling from payphones so that their conversations could not be tapped. In the first few months after Rüdiger returned to Europe, his father, who had been diagnosed with rectal cancer, would say, “It would be nice if you came.” Finally, as his illness worsened, Heim had simply said, “It is time now for you to come.”

By that point Aribert Heim did not leave the Kasr el Madina hotel, in a working-class neighborhood of Cairo. A nurse visited each day to check on him and to change his colostomy bag. His room was next to that of Mahmoud Doma, the son of the hotel’s former proprietor and a 22-year-old engineering student, and if he needed something he would knock on the wall. Mahmoud was not yet 10 when Heim had moved into the establishment, and the Austrian—who gave him books to read, taught him languages, and played ping-pong with the Doma children on the roof—eventually became a father figure for him after his own father passed away. As Mahmoud understood it, the man he called Amu Tarek, or “Uncle Tarek,” had moved to Egypt because of a problem with his back, which healed in Egypt’s warm, dry climate. Mahmoud also knew his friend had a wife and two sons back home in Germany, but they did not come to visit.

As his life slipped away, however, Heim became more candid. His cover story with so many Egyptian friends—Alfred Buediger, the owner of a demolition company—was gone and he told Mahmoud that he had been a doctor who used to study women’s cancer. “He said he was very famous and a very good doctor,” Mahmoud said. Heim never told him anything about his military service.

Toward the end he asked his young friend, “Can I donate my body after I die, so that the university can use it for tests?’” Mahmoud said it was because his Uncle Tarek had an unusual illness, and hoped that before he was buried the students at the medical school could learn from his body. “I told him that our Islamic beliefs did not allow you to donate your body. It is a sin.”

“All right,” Heim said. “If that is so then it does not have to happen.’”

When Rüdiger entered his father’s room in the Kasr el Madina, the lights were off, and Heim was sitting in a wheelchair. Rüdiger greeted his father.

His father returned his greeting, then immediately turned to practical matters. “We have to decide now if I’m going to remain in this chair for my final days or if I’m going to lie in the bed.” He refused to discuss recovery, remission, or improvement. Rüdiger learned most of what he needed to know just by looking at the weakened state of his father’s once-powerful body. Moving from the wheelchair to the bed to sleep at night had become an excruciating ordeal. Heim finally said, “From now on I will be in the bed.”

The following day Rüdiger helped his father lie down. “He was a moribund, doomed person, slowly rotting from the inside,” Rüdiger said. His pain was compounded by a return bout with kidney stones. At one point the agony was so overpowering he demanded that Rüdiger give him all the pain-killing medication they had at once.

For nourishment, he took only warmed milk. “Milk has everything in it that the body needs, and I don’t need any more than that now,” Heim said.

Father and son spent much of the time watching the Barcelona Olympics. When the Olympics were not on they tuned to coverage of the war in Bosnia. On the matter of the criminal case he was now facing, the dying man expressed conflicting wishes. He said at one point that he wanted “the truth to come to light,” but at another he told his son, “Don’t worry about this nonsense anymore.”

At a certain juncture, his pain was so great that Heim could no longer roll over to urinate, and short of taking him to a hospital for a catheter to be inserted, Rüdiger had to help him pee every two or three hours. When Rüdiger made a mistake, the bed would be soaked in urine and it became a major production to move his father to change the sheets. Rüdiger had taken to massaging his father’s arms and legs because he noticed that it helped with the pain.

“I also caught myself thinking that the suffering actually had to end, that it was too much, that it was outrageous,” Rüdiger said. “And one discovers, too, in oneself, the weakness to hope that it stops, and it is actually a shameless thought, a terrible thought,” thinking ahead to his father’s death. At one point Rüdiger went to the bathroom and wept. He was sure that in Europe no one would have to die like that.

Heim’s voice gave out several days before he passed away. Rüdiger blamed himself for dallying in Europe before coming to Egypt. He had lost his last chance to ask the lingering questions he had about his father’s past.

On August 9, 1992, Aribert and Rüdiger Heim watched the closing ceremonies of the Olympics. Dr. Heim fell asleep at around 10 p.m. Instead of going back to the Scarabee to sleep, Rüdiger now had a thin mattress that he rolled out in front of the balcony. Around one o’clock in the morning, he noticed that his father’s breathing was slowing. Over the course of hours, his father had hinüber gedämmert, “faded across.”

“There was no exact time of death, but at some point he had stopped breathing,” Rüdiger said. He spoke to him, checked to make sure his father was not still alive and placed his hand over his father’s head. When it was clear he had died, Rüdiger took a piece of white cloth and ran it under his father’s chin, tying it at the top of his head. He had learned when his grandmother died that this was necessary, so that rigor mortis would not leave his mouth hanging open.

“One says goodbye in a very personal way,” Rüdiger said. He smoked a cigarette on the balcony, staring out into the Cairo streets. Then he went downstairs and notified the hotel’s night porter that his father was dead. The porter reached Mahmoud, who had been away in Alexandria. The young man arrived with his mother and one of his brothers within a few hours. The hotel also notified the authorities. A representative from the German embassy came to Heim’s deathbed, as well as the Egyptian official who filled out the death certificate.

Ever wary of the authorities Rüdiger gave them his Danish driver’s license as identification. He also put down a false birthday for his father, to further throw off anyone trying to find Aribert Heim. Rüdiger said Heim did not want investigators to bother his family and he did not want trouble for the Domas.

Sometime after sunrise, two men came to bathe his father one final time. They took the body out into the hall where they had set up a table. They took off his clothes, removed the colostomy bag, and began to wash him according to the Islamic ritual known as kafan. Mahmoud didn’t want Rüdiger to watch but the Egyptian man cleaning his father said, “Come, look at this. This is your father.” When they were done with the washing, they wrapped him in long white winding sheets.

It is Muslim tradition to bury the body as quickly as possible, without embalming or autopsies. Mahmoud wanted to inter Uncle Tarek in the same tomb with his own father. Rüdiger wanted to honor Heim’s wish that his cadaver be used for medical research. Mahmoud tried to explain that it would be simplest if he were buried according to local custom, but the son refused. The man from the German embassy, an Arab who spoke German, finally told Mahmoud that as the son, Rüdiger had certain rights in deciding what would happen to the body. Mahmoud did not like it, but he remembered his Uncle Tarek’s request and reluctantly went along.

The body was carried downstairs to a waiting mortuary van where it was laid out on a wooden bier in the back. Mahmoud cried. “He was like a father. He loved me and I loved him. He was the same as my father.”

Mahmoud and Rüdiger, the son Mahmoud knew only as Roy, drove to several hospitals but none of them wanted to take the corpse. It was an unusual request with possible legal repercussions. The orderlies told them that they could not accept corpses for donation. After several hours, Rüdiger began to wonder if his father’s body was beginning to putrefy. Mahmoud said finally, “That’s enough. We can’t go on like this. Let’s first of all put him in a refrigerator. You’re more than welcome to keep looking, but I’m tired.”

They eventually found a man at one of the hospitals who was willing to take the body. The details were sketchy. He may have been bribed, or simply offered to do them a favor by keeping Heim’s body overnight. Either way the two men left his body there. Rüdiger believed that the body had been accepted according to his father’s last wishes. Mahmoud described the arrangement as more temporary.

When the two returned to the Kasr el Madina, they sorted through Heim’s belongings, packing his father’s papers into an old leather briefcase and a hard-shell Samsonite case. Once this was done, Rüdiger told Mahmoud to watch his father’s effects and said he would soon return for them. He did not give his address or any way to contact him. Mahmoud found it strange at the time but did not ask any questions. He may have had an ulterior motive in helping to speed Rüdiger’s departure. For once the son left, Mahmoud went back to try to claim Heim’s body so that he could be interred in his family tomb, as he had wanted to do in the first place. The hospital told him that he may have called the man uncle, but that did not make him a legal relative. Corpses were not just given out to anyone who wanted them.

In the end, Tarek Hussein Farid was buried in a common crypt like an Egyptian pauper.

This post is adapted from Nicholas Kulish and Souad Mekhennet's new book, The Eternal Nazi, to be published March 25 by Doubleday.