Katelyn Jones was charged Wednesday with making threats of violence with a phone and through social media.
Jones' target was Monica Palmer, a Republican member of the Wayne County Board of Canvassers, and her family, investigators said.
Jones, 23, has ties to Olivet, Michigan, but was arrested on a criminal complaint, a temporary charge, in December in New Hampshire, where she was living with her mother.
Jones sent photos of a dead body and threatened Palmer on Nov. 18, the FBI said.
Monica Palmer, Wayne County Board of Canvassers.
She apparently was upset that Palmer and a fellow Republican on the four-member Board of Canvassers initially refused to certify Wayne County's election results on Nov. 17, typically a routine step on the way to statewide certification.
They subsequently certified the totals in favor of Joe Biden after people watching the public meeting on video conference criticized them during a comment period.
A message seeking comment from Jones' attorney wasn't immediately returned Thursday. Jones was ordered to participate in mental health treatment when she last appeared in Detroit federal court on Jan. 19.