JACKSONVILLE, Fla. -

A 47-year-old Jasper woman has pleaded guilty to sending letters to the offices of Sens. Marco Rubio and Bill Nelson in June 2011, threatening their lives.

Kathryn Allen faces up 10 years in federal prison and a fine of $500,000. A sentencing date has not yet been set.

According to court documents, on June 27, 2011, Allen mailed threatening letters containing a white powdery substance to the offices of Rubio and Nelson. Both offices were evacuated as a result.

Field and laboratory testing determined that the white powdery substance was not hazardous.

Allen admitted that she sent the letters in an effort to frame her neighbor, who she believed was engaged in an interracial relationship.

Allen was implicated in the scheme when her handwriting was identified in each of the letters.