A survivalist accused of ambushing two state troopers, killing one and seriously wounding the other, was captured by US marshals near an abandoned aeroplane hangar.

Mexican drug cartels whose operatives once rarely ventured beyond the US border are dispatching some of their most trusted agents to live and work deep inside the US — an emboldened presence that experts believe is meant to tighten their grip on the world’s most lucrative narcotics market and maximise profits.