"""PICTURED: Border Patrol agent, 36, killed by 'rock throwers' in ambush attack near US-Mexico border in Texas that also injured his partner""" Agent Rogelio Martinez, 36, was killed while responding to activity at the border Authorities said his partner is also in serious condition following the incident FBI has taken over the case and officials are currently searching for suspects and witnesses President Donald Trump tweeted: 'We will seek out and bring to justice those responsible. We will, and must, build the Wall!' Authorities were searching Texas' Big Bend area for suspects and witnesses Monday after US Customs and Border...