The Reno, Nevada Police Department is the second law enforcement agency in the country to use Megan's Mapper, a software program that uses geographic mapping to notify residents when a sex offender moves into the neighborhood.  The program can generate thousands of notification letters in minutes, track where sex offenders live and create databases of sex crime convicts who are not required to register.  It is estimated that the new system can do in 30 minutes what would have taken a week to do before.  Police say that the mapping software also gives them a new investigative tool by providing instant information on an offender such a photographs, physical characteristics, employment history, vehicle registration data, victims and prior arrest records.