(Portland, OR)  --  Police say they've arrested two teenagers in connection to a string of TriMet thefts and robberies.  Police arrested 15-year-old Michael Perkins and 17-year-old Markel Jones late last week.  Police believe the teens stole unsecured items from passengers on TriMet trains over the course of three months.  They're also accused of robbing a man of his backpack and then beating him.