under surveillance

See: guarded
References in classic literature ?
As I passed along the corridors between the banquet hall and the apartments that had been allotted me, I had a sudden feeling that I was under surveillance, and, turning quickly in my tracks, caught a glimpse of a figure which darted into an open doorway the instant I wheeled about.
All these were Government spies, then, and every spy was under surveillance himself--men spoke in whispers in Venice, and no man trusted his neighbor--not always his own brother.
I think they are here," replied Tarzan, "to prevent us from going some place that they do not wish us to go; in other words we are under surveillance, and possibly as long as we don't go where we are not wanted we shall not be bothered.
They grasped at a myriad clues; hundreds of suspects were jailed, and at various times thousands of suspicious persons were under surveillance, but nothing tangible came to light.
Only criminals need to worry about being under surveillance, the 35-year-old music company executive said.