Detective Lenses are a Tinkering craftable item that players can use to determine another player's Thieves Guild membership or determine which players have looted a corpse
Players use Detective Lenses by double-clicking them and targeting a player or corpse within 4 tiles
Players can use a Detective Lens at most once every 10 seconds (counts as a Detect Hidden skill usage)
Players need to have 80 Detecting Hidden skill or above to use a Detective Lens
Targeting a Player will privately inform you if the target is a member of the Thieves Guild and what their Membership type is (Grey Hand or Red Hand)
If you are in the Thieves Guild and another player uses a Detective Lens on you, you will be notified of such
Targeting a Corpse will reveal the names of all players that have Lifted or Used items on the corpse