Convicted sex offenders remain on the registry for 20 years after the date of their conviction, if they have one conviction.

Those convicted of more than one sex offense remain on the registry for life.

The process of public notification varies with each level.

The names of level one offenders are only available to people who live within a one-mile radius of where the offender lives or works.

People can obtain the names of level one sex offenders by submitting an application at the Cambridge Police Department.

Currently the Department has received 18 such requests, Dillon said.

Information about level two offenders is automatically forwarded to schools and day-care centers within the city of Cambridge.

Individuals who are the director or manager of a community agency or organization that has care, custody or protection of children or others who need special protection...or whose clientele are likely to encounter sex offenders are able to put a request in writing asking to also be included on the level two notification list," Dillon said.

"We have approximately 200 organizations on that list," Dillon said.

Currently there are no level two offenders living or working in Cambridge Dillon said.

The name, picture and physical description of level three offenders must be publicly posted.

Currently the Criminal History Systems Board is in the process of identifying individuals who are required to register because they have been convicted or adjudicated of a sex offense. The board also is responsible for classifying the more than 13,000 currently identified offenders.

Cambridge Police spokesperson Frank T. Pasquarello said the individuals accused of murdering 10-year-old Jeffrey J. Curley were not required by law to be on the registry since they had not committed any previous offenses under the names they gave to Cambridge Police.