A little-known person

[RJNorton]

IMO, the two most likely possibilities are (1) McDevitt told the truth and our mystery person in the street suggested to the group of detectives that they go to the Surratt boardinghouse or (2) Superintendent Richards was already suspicious of the boardinghouse (maybe acting on Gleason's information) and specifically ordered Clarvoe, McDevitt, and the other detectives to go to the Surratt boardinghouse.

Steve, the John Surratt trial testimony is here

https://archive.org/details/trialjohnhsurra00surrgoog

but my old computer does not seem to be able to find Clarvoe's testimony. I have numerous books that say he did indeed testify. All I am curious about is if he is asked about how the detectives ended up at the Surratt boardinghouse.