liz norden 's adult sons , jp and paul , each lost a leg when they were hit by the explosive mix of shrapnel and ball-bearings unleashing by the tsarnaevs ' primitive explosives in april 2013 .
the men , now in their mid-thirties , were received horrific wounds as they shielded friends from the second of two blasts which went off by the finish line at the boston marathon almost two years ago .