The on-sale date is from the publication date recorded in the Catalog of Copyright Entries, Third Series, Vol. 1, Part 2, Nos. 1&2, Periodicals, 1946-1947.
Lieutenant Jon Jarl (of the Space Patrol); Xezxkj [as Joe] (native of the planet Mercury); Charles Galton
Synopsis
A presumed killer takes flight and lands on Mercury, where he is befriended by a native Mercurian. But when Jon Jarl arrives by ship to take the earthling back home, the Mercurian automatically assumes the earthling may be innocent of the crime [as he was told] and fights to protect him from the Space Patrolman.