Sascha Pinczowski posted on Facebook after the November Paris attacks that "Ignorant spreading of anti-Muslim sentiment and propaganda does nothing but benefit ISIS."
The 26-year-old Pinczowski was a Dutch national living in New York. She and her brother, Alexander, were among those killed in Brussels.
Pinczowski's November 16 Facebook post was reposted by her mother, Marjan Pinczowski Fasbender.
The mother wrote that she wanted to share "this message of tolerance from our Dear Daughter Sascha."
The private Facebook post was provided to The Associated Press by James Cain, whose daughter, Cameron, was engaged to Alexander Pinczowski.