She came from the actors family Krüger-Demmer and died at the age of 30 after a successful stage career in Vienna lasting only 15 years.
Theklas parents were the acting couple Caroline, née Krüger, and Carl Demmer.
Kneisel, née Demmer, one of the most popular members of the Theater an der Wien, after surviving gastroenteritis died of a nervous fever.
[...] Yesterday at 3 o'clock the solemn funeral took place in the Karlskirche in which mourning art lovers and many members of the local stages were not missing.
her death was also greatly regretted: The friends of this theatre will painfully miss the serenity which this humorous artist, in happy emulation of the genius Krones who also passed away too quickly, understood to spread.