But critics accuse the publicity-prone Arpaio of exploiting the school tragedy for self-promotion. They also question the effectiveness of random patrols outside school grounds without input from school administrators and state government.
"The events in Newtown should be addressed by the governor, legislature, and county and local officials," Randy Parraz, president of Citizens for a Better Arizona, said in a statement.
In her State of the State speech earlier this month, Gov. Jan Brewer (R) proposed more resources to place armed officers inside schools but opposed the idea of arming teachers, as some people across the country have suggested.
Arpaio says trying to get various groups to agree on the best way to tackle school safety could take months. And he saw fit to take quick action on his own.
"Unfortunately, you've got a lot of politics involved in this," he says.
Patrolling outside schools in communities north of Phoenix is just the latest job for members of Arpaio's posse – many of them retirees like Mr. Bennett. Seeking extra help for his department, Arpaio created the posse in 1993 to patrol malls during the holiday season. Today, they check in when people call police worried about someone's health or safety, transport injured inmates to hospitals, and help with traffic control. They also provide security during the sheriff's controversial workplace raids targeting immigrants working in the country illegally.
A local CBS affiliate, KPHO-TV, investigated the posse and found some volunteers have a criminal history that includes offenses such as assault, drug possession, and domestic violence. More than 400 of the 3,000 posse members carry firearms.
The sheriff stands by his posse and says its saves millions in taxpayer money. The same taxpayers would be responsible for any mishaps involving posse members while on the job.