**_Detectives track down a mad bomber on the loose in Los Angeles_** Shot in the spring of 1972 and masterminded by Bert I. Gordon, this is a psychological crime thriller focusing on a mass murderer in the low-budget tradition of “Targets” from 4.5 years earlier. It would be followed by “Hitch Hike to Hell” and “Murderlust.” All of these analyze the mental wiring of society’s misfits who turn to murder. “Falling Down” would give the basic plot a blockbuster budget in the early 90s. A bit o’ humor is added with towering Chuck Connors having furious tirades over regular folks who make him…