DESOTO, Texas - A 19-year-old is waiting to be extradited back to DeSoto after police determined he was responsible for a shooting that killed one and injured another while a 5-year-old in their car watched on in horror last week.Police said surveillance video and old fashioned police work helped them track down Evan McMaryion in Arizona.The shooting happened on May 15, as 34-year-old Randall "Scott" Thornhill and 29-year-old Heather French were sitting in a 2003 Mazda 3 with French's 5-year-old son in the 300 block of South Elerson Road.The 5-year-old was being dropped off to his father, who lives and works at a farm, but his father hadn’t arrived back home yet.