(NewsNation) — Alice and Ellen Kessler, the twin sisters who made up the musical group touring Europe and quickly gaining fame, died by joint assisted suicide.

The German Society for Humane Dying, an organization that the twins were part of for more than a year, told The Guardian that the twins had been considering the option of assisted suicide for some time, and a lawyer and doctor had a discussion with them about the process. They added there were no mental health issues with the twins.

“People who choose this option in Germany must be absolutely clear-headed, meaning free and responsible,” a spokesperson with the organization said. “The decision must be thoughtful and consistent, meaning made over a long period of time and not impulsive.”

In 2020, Germany’s highest court overturned a ban on medically assisted suicide, ruling the previous law was unconstitutional and that the constitution includes a right to a self-determined death.

During an interview with Italian news outlet Corriere della Sera in 2024, the sisters said it was their wish to die together, adding that “the idea that one of the two will go first is very difficult to bear.”

The twin sisters were born on Aug. 20, 1936, in Germany, where they trained as ballet dancers during their childhood, and fled to West Germany in the 1950s, where they were able to propel their career. They also saw success in the U.S., making an appearance on “The Ed Sullivan Show” and performing alongside artists like Frank Sinatra and Fred Astaire.

The Kessler Twins were 89.