Snatched by scientists at birth in 1950 and subjected to torturous “experiments” in Moscow, conjoined twins Masha and Dasha Krivoshlyopova were treated as guinea pigs while their mother believed they had died.
Known as “the two headed girl”, the twins were joined at the spine at an angle of 180 degrees, shared a blood system and had one leg each.
The pair, who lived to age 53 to become the world’s oldest conjoined twins, were placed in Stalin’s Soviet Academy of Medical Sciences Pediatric Institute.
For the next six years, a team of physiologists burned, froze, starved, electrocuted and kept the girls forcibly awake in the name of science. They were kept in a painted glass box they couldn’t see out of, and injected with radioactive and other toxic substances.
They had separate nervous systems, so scientists would inject one of the girls, and assess the other for reactions. Other times one of the girls would be placed into a tub of icy water to observe how it affected the other’s body temperature.
After years of living in a laboratory, they were transferred to the Central Scientific Research Institute of Traumatology and Orthopedics in 1956 where they were taught to walk and given a primary education.
For the next eight years the Masha and Dasha were kept hidden in a children's ward before attending a boarding school for children with motor-impairment in southern Russia.
As adults, neither of them could remember anything of the experiments and were astonished to see a documentary film made about them by the Academy of Medical Sciences, which detailed the horrific experiments.
“They had remarkably good memories, perhaps because they shared them with each other and would look back on their lives together often,” said journalist and author Juliet Butler, who befriended the pair and has now written a novel based on their lives.
Despite being subject to the same isolated childhood, the twins grew up with polarising personalities.
“Dasha was the sweet one from early childhood. Always eager to please, empathetic and kind,” Ms Butler told 7 News Online.
“She was popular at school because she was willing to help disabled students who were unable to do things for themselves and loved being useful and helping people. She was gentle, thoughtful and intelligent.
“Masha had a completely different character - also from early childhood. She was quick to anger, disobedient and tended to think of herself rather than taking other people’s feelings into account.
“She used to get so frustrated at having Dasha ‘attached’ to her that she would shout at her and hit her. From the age of six the relationship between the two of them became established as Masha being the controlling one and Dasha the submissive one.”
When Dasha fell in love with a boy at school, Masha prevented the relationship from developing, because she didn’t want to share her sister with anyone.
“Masha liked Slava but became angry if he tried to kiss Dasha and refused to contemplate that the two of them should have a relationship which would sideline her. She wanted to be the only one that Dasha loved. This situation eventually led Dasha to contemplate suicide,” Ms Butler told.
When the option of surgery to become separated was floated, Masha quickly shut it down despite Dasha being open to the idea.
In 1985 they tracked down their birth mother Yekaterina Krivoshlyapova and she visited them for four years before Masha broke off the relationship.
However, despite the emotional abuse, Dasha loved and respected her sister.
Masha died of a heart attack on April 17, 2003. Because there was no option for separation at that point, Dasha was told her sister was just sleeping and that they would both be fine, Ms Butler said.
“Dasha of course would have known the moment Masha’s heart stopped beating.”
The surviving twin was taken to hospital and died 17 hours later due to blood poisoning from the toxic by-products of Masha's decomposing body.
Ms Butler admired Dasha’s compassion and resilience in being denied the independent life she longed for.
“I was filled with awe and respect for how she accepted her situation and seemed to cope with Masha. She had no choice of course, but I could see that despite all her frustrations she very much loved Masha,” she said.
The Less You Know the Sounder You Sleep by Juliet Butler will be published on August 21 by HarperCollins, RRP $27.99.