Manigault is best known for competing on various incarnations of Donald Trump's "Apprentice" franchise.
Her brother was shot in the head early Sunday while he slept at his Youngstown home. His girlfriend's ex-boyfriend was arrested a short time after the slaying, the Vindicator newspaper said on its Web site.
"We thank everyone for their amazing outpouring of support surrounding the tragic death of my brother Jack. ... Right now it is an extremely difficult time and we ask that you allow family privacy to grieve and make all necessary arrangements," Manigault said in a statement issued to the newspaper.