put someone off the scent
put (one) off the scent
1. To cause an animal, especially a dog, to lose the scent of someone or some other animal, as by distracting it with other odors. I've heard that you can put dogs off the scent by crossing back and forth through a river. The hunter covered himself in elk urine to put his prey off the scent.
2. By extension, to misdirect one away from their pursuit; to steer one's investigation or suspicions in the wrong direction. The mafia accountant managed to put the authorities off the scent of the mob's money laundering for years, but they finally caught up with him after an anonymous source tipped them off. That outlier data put me off the scent for a while, but I think my research is back on track now.