Authorities recently released details of two notes received in the days following her disappearance. The release was intended to help investigators identify the person responsible for writing them.
According to reporting from ABC News, the release produced a "slight increase" in tips to investigators.
The notes have become an important part of the investigation because investigators are asking members of the public to look closely at the handwriting, wording and other characteristics that might help identify their author.
The decision to release the material months after Nancy disappeared demonstrates how investigators are continuing to pursue new avenues.
It also shows how difficult the case has become.
When a missing-person investigation reaches six months without a recovery, investigators must examine old evidence from new perspectives while continuing to follow fresh information.
A Second Message Deepened the Mystery
The case became even more disturbing after a second communication reportedly claimed that Nancy had died.
