PHOENIX, Ariz. -- Phoenix police are worried the so-called "Fused Bandit" is becoming more confident and violent in his month-long robbery spree.

• Raw Video: 'Fused Bandit' Getting More Brazen

The armed robber earned his name when he first started robbing auto parts stores and would ask the clerk for a box of automobile fuses before pulling a gun.

Police said it's a technique he's used at least 16 times in the past month to rob stores ranging from auto parts facilities to fast food restaurants and even dry cleaners.

Police said no one has been hurt but the gunman has become more bold and more demanding in his robberies, and officers worry it may escalate even further.

Officers said security video shows he wears a baseball cap and long-sleeve hooded sweatshirt during the robberies and carries two different weapons, a silver and a black handgun.