Mutt & Jeff had seen their circulation base dwindle by the time I was able to read, such that I don't recall ever seeing the strip in any newspapers growing up.
Bud Fisher's legendary duo were first introduced early in the 20th century, with Mutt debuting as a solo act in 1907. Nearly a decade later, the duo began appearing in a series of silent short cartoons, some of which are now available on YouTube.
Take, for example, "Slick Sleuths", from 1926, in which we find the boys as would-be detectives.....
The Phantom, the villain of the piece may have the same kind of abilities as Mickey Mouse's later nemesis, the Phantom Blot, but that's about it. This Phantom came across as non-descript, and as interesting as watching paint dry.