Answer: shadowed

AnswerCrossword Clue
SHADOWEDKept tabs on
SHADOWEDFollowed stealthily
SHADOWEDFollowed secretly.
SHADOWEDPut a tail on
SHADOWEDTailed
SHADOWEDSurveilled, say
shadowedFollow and observe (someone) closely and typically secretly
shadowedSHADOW, to make dark or gloomy
shadowedEnvelop in shadow; cast a shadow over
shadowed(of an opposition politician) Be the counterpart of (a government minister or a ministry)
shadowedAccompany (someone) in their daily activities at work in order to gain experience at or insight into a job