During the First Wizarding War, why didn't Dumbledore just hunt Voldemort down, as he had done with Grindelwald?
By 'hunting down', I mean finding, defeating and imprisoning him, exactly as in Gridelwald's case, and not, say killing him, something which Dumbledore would not do, as the answers to a previous question (as to him not hunting down Death Eaters) show.
Dumbledore knew that Voldemort had delved into the Dark Arts deeper than anyone else in history and hence "had powers he will never have". But he must have also known well that he could have defeated Voldemort at a direct confrontation, given that he had defeated Grindelwald earlier even against the Elder Wand, and now had that same wand at his disposal. He is seen confident about this throughout the series.
At the Battle of the Department of Mysteries, he did not go beyond outweighing Voldemort and forcing him to flee, probably because, by then, he had reasons to suspect that there was more to Voldemort's survival than his physical body, and thus, destroying that body which had Harry's blood without permanently disposing him off would not have been wise.
But why did he not do that at the First Wizarding War? Is it just that they could not track him down, or did he suspect even then that Voldemort had more sinister things about his soul? is there any canon confirmation of the latter suspicion?