
Karl Tanzler becomes Carl Von Cosel
Karl Tanzler left his wife and children in 1927 and moved in Florida. There, he changed his name to Carl Von Cosel and started working in a hospital where patients with tuberculosis were treated. He also claimed that during his childhood he had visions of his dead ancestor Countess Anna Constantina Von Cosel (one of the reasons why he changed his name) who told him that his true love will be a dark haired exotic woman. Whether that claim is true, we do not know, but he did meet his exotic love.
Meeting Elena Hoyos

The death of Elena Hoyos
In 1931, just before Halloween, Elena died and was buried in an above-ground mausoleum ordered by the doctor, because he thought that groundwater would have contaminated her body. He would regularly go to her grave and take care of it, which didn’t alarm her family since they trusted him and knew his special connection with her. Little did they know that he was trying to take Elena’s corpse from the grave as his connection with her was more than anyone could possibly imagine. During his visits to Elena’s grave he had long conversations with her and he even installed a telephone so that he would feel close to her even when he was away. Apparently, he also had seen her ghost telling him that he needed to take the corpse and he was also trying to preserve her body with formaldehyde.
When obsession becomes pathological

I made the examination in the funeral home. The breasts really felt real. In the vaginal area, I found a tube wide enough to permit sexual intercourse. At the bottom of the tube was cotton, and in an examination of the cotton, I found there was sperm. Then I knew we were dealing with a sexual pervert.
The discovery and arrest
Elena’s sister wasn't seeing doctor Von Cosel at the tomb anymore and there were also some rumors that he was behaving bizarre, so she began to believe that something might have happened, especially since he showed a morbid obsession since the beginning. She asked the authorities to open the tomb and was surprised to see that the body of her sister wasn’t there anymore. When confronted Von Cosel, he invited her inside and she was obviously shocked at the sight of the sinister image created by him. He was soon arrested and found mentally capable to stand trial on the charge of "wantonly and maliciously destroying a grave and removing a body without authorization." However, the case was dropped and he was released. Elena's body was showed to the public, almost 6,800 people, before her last burial.
Later life and death
He moved in Pasco County, Florida in 1944 where he apparently used a death mask to create a life-sized effigy of Elena. It has been speculated that he had taken the body of Elena even after his arrest but there was no evidence that the effigy he created contained any human material. However, his morbid obsession continued until his death in 1952 as he lived the rest of his life with the second doll that resembled Elena.
Sources:
VON COSEL
Undying Love: The True Story Of A Passion That Defied Death
Skullduggery: 45 True Tales of Disturbing the Dead
A short documentary about this case: