at the sight of someone—on seeing a person:
- Does running away at the sight of the police give officers reason enough to stop and search you on the street?
in the sight of someone—
1. near enough to be seen by a person:
- He was brutally killed in the sight of the townspeople.
2. in a person’s opinion; as regarded by smb.:
- In the sight of the world, they were a happily married couple.