Eventually, authorities caught up with the entire so-called Barker-Karpis gang.
Herman, the oldest, killed himself after being wounded during a shootout with police. The next oldest, Lloyd, was shot and killed by his ex-wife soon after he was released from serving a 25-year prison sentence. Arthur, or "Doc," was shot and killed by prison guards when he tried to escape from Alcatraz.
FBI agents tracked Freddie and Ma Barker to a cottage in Lake Weir, Fla. in 1935, the only known instance that Barker herself carried a machine gun. Barker and Freddie were killed during an hours-long shootout with the feds.
Karpis was arrested the following year and imprisoned until 1969. He later wrote an autobiography, then moved to Spain, where he died from natural causes in 1979.
Phoenix police believe Roberson and the youngsters committed at least 20 robberies involving assaults on victims between the age of 13 and 20. One 13-year-old was beaten and forced to empty his pockets — which contained only a lollipop. One victim suffered a concussion.
Roberts said the group's downfall came after one of the boys spotted someone he had robbed the day before at a grocery store, went up to him and said: "I remember you — you're the guy I punched in the face yesterday."
On May 29, Phoenix detectives were about to serve a search warrant at Roberson's apartment when she and some of the boys got in the SUV and left.
Police pulled the group over and arrested them; Roberts said detectives believe the group was on the way to commit a robbery.
Police believe that if Roberson and the others hadn't been caught when they were, their crimes could eventually have become much more serious.
"What I see is when people start off doing small crimes, and they become successful at those crimes — especially when they're violent crimes — the violence seems to escalate," Roberts said.
Copyright 2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.