Well, technically yes it can. However, since detect spells need to focus 3 rounds before pinpointing a person location, its a highly ineffective method when compared to See Invisibility (not Detect Invisibility). If the invisible evil guy moved out of the Paladins current spell arc, your Paladin would have to shift his evil-mojo-detecting eyes and start over from round one. Detect Magic can also be used in this (ineffective) way.
Slander