That crook needs a name! Mr. Green, because of his bright green suit?
We know he's a criminal because he's the only man not wearing a tie.
In the Adventure 247, the first page (in the Archives) shows the three legionnaires attacking a "criminal getaway rocket" - but the incident isn't followed up in the story and we don't see any actual criminals.
It would be interesting to catalogue the Legion missions and see how many were rescuing people from disasters and how many were capturing criminals/villains.