Is he a hunter gone mad? A schizophrenic with delusions of a direct line to God? A military marksman waging urban warfare on his countrymen? A terrorist? And whoever he is, is he working alone?The science of US law enforcement has had ample experience with murder, but the sniper who has terrorised the greater Washington area in the past week, killing seven and wounding two with single-shot precision, is confounding at least 195 of the nation’s finest.The latest in what have been frustratingly few clues is a tarot card inscribed, ‘‘Dear policeman, I am God,’’ discovered near a shell casing 150 yards from the Maryland middle school where a 13-year-old boy was critically wounded on Monday. ‘‘I am a profiler, not a soothsayer,’’ said Clint Van Zandt, a retired FBI official and an expert on criminal psychology, voicing the challenge faced by investigators struggling to solve the series of crimes.‘‘He is motivated, he is focussed, he is reasonably intelligent for a predator. He is psychopathic and has no appreciation for the pain and consternation he is causing.’’A sniper as serial killer is not unprecedented, but cases that leave so little evidence tend to stump even the best detectives. Police on Thursday confirmed that ballistics evidence linked the shooting to death of a man in Manassas, Virginia, to eight other seemingly random sniper attacks in the US Capital and four nearby counties. (LATWP with Reuters)