Who Stole the Cat? (Who Stole What from Whom? Part III)

One day a cat was stolen. Mike, Spike, and Slug were again rounded up for questioning. Mike claimed that Spike had stolen it, and Spike claimed that Slug had stolen it. Now, it was not certain that any of the three suspects had stolen it, but later investigation showed that no guilty person told the truth and no innocent person lied. Also, the cat was not stolen by more than one person.
Can it be determined who stole the cat?

(Source: King Arthur in Search of His Dog and Other Curious Puzzles by Raymond Smullyan)

If Mike stole the cat then Spike's accusation is false, which is not allowed, letting him off the hook. The same reasoning applies to the possibility of Slug being the thief: Mike is falsely accusing Spike. It can't be the case that no one stole the cat because in this case, not one but two false accusations are being made. Therefore Spike stole the cat.