WASHINGTON (CNN) -- During a recent legal conference, retired Supreme Court Justice Sandra Day O'Connor talked publicly about a little-known attempt last year to poison her and her colleagues.

In fact, Barbara Joan March, a 60-year-old Connecticut woman, was sentenced last month to 15 years in prison for sending 14 threatening letters in April 2005 -- each with a baked good or piece of candy laced with rat poison -- to the nine Supreme Court Justices, FBI Director Robert Mueller, his deputy, the chief of naval operations, the Air Force chief of staff and the chief of
staff of the Army.

March pleaded guilty in March to 14 counts of mailing injurious articles.

The letters did not seem to pose much of a real danger since the threatening note told therecipients the food was poisoned. In court papers submitted with the plea agreement, prosecutors said each of the envelopes contained a one-page typewritten letter stating either "I am" or "We are" followed by "going to kill you. This is poisoned."

Supreme Court spokeswoman Kathleen Arbergh said the poison packages never reached the chambers of the justices.