Born in West Islip, New York, Seibel graduated from Princeton University with her Artium Baccalaureus degree in 1982 and later from Fordham University School of Law with a Juris Doctor in 1985.
From 1993 to 1997, Seibel was Assistant United States Attorney for the Southern District of New York before serving as AUSA-in-Charge of the White Plains Branch from 1997 to 1999.
Seibel was a Senior Trial Counsel with the United States Attorney's Office from 1999 to 2005.
She was appointed Deputy U.S. Attorney for the Southern District of New York, where she served from 2005 to 2008.
Seibel was nominated to the United States District Court for the Southern District of New York by President George W. Bush on March 11, 2008 to a seat vacated by the death of Judge Richard C.