New York (CNN) -- Faisal Shahzad made a practice run in Manhattan the day before he allegedly tried to blow up a car bomb in Times Square, according to a law enforcement source with knowledge of his questioning. Last Friday, Shahzad drove his white Isuzu from Connecticut through Times Square, where he staked out potential locations for the following night's planned attack, the source said. He then parked the Isuzu several blocks away from Times Square, though the precise location was unclear, and took a train back to Connecticut, the source said. On Saturday night, with his recently acquired Nissan Pathfinder loaded with his makeshift explosives, Shahzad drove southbound along Manhattan's East River on FDR Drive to the 49th Street exit, the source said.
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NEW: Isuzu driven from Connecticut to Times Square day before planned attack
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NEW: Shahzad accidently left keys to the Isuzu inside the bomb-laden Pathfinder
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Shahzad felt Islam was under attack, source says
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"The dynamic appeared to have changed in the last year," official says
Shahzad then pulled over and reached into the @placeholder's rear compartment where he attempted to set into motion the process needed to set off the homemade bomb, the source said.