The woman presented a mug of tablets to her brother and said "you can become an angel", or something similar.
She claims that her brother wanted to die, and that she helped him with that.
The woman was sentenced in Jönköping District Court to six years in prison for murder.
The sentence was later increased by the Court of Appeal, and the crime title was then also changed to murder.
The verdict was appealed, but HD writes in a decision on Friday that they have not found any reason to try the case.
The death occurred in the man's home in Gislaved municipality in November.
According to several witnesses who were questioned in the trial, the man was afraid of dying, and often said that he wanted to "live his whole life".