The Sharon Police Department wants to raise awareness that the town offers a tracking service for residents who have health conditions that may cause them to wander, Patrolman Andrew Pacino said. Participants, who wear a signal-emitting bracelet, are often elders with dementia or children who have autism. “It can save lives by cutting down the time it takes to find somebody,” he said. About six residents use the system, which the town has offered for several years, Pacino said. The cost of the device, the LoJack SafetyNet, is $99 to register plus $30 a month in Norfolk County, according to William Knight, chief of staff for Norfolk County Sheriff Michael G. Bellotti. The sheriff’s office was the first agency in New England to adopt the system and oversees billing for some communities, he said. About 125 people in the county participate, and about 78 rescues have been made since 2006, he said.