Who Stole the Horse? (Who Stole What from Whom? Part V)

One day, a horse was stolen. Again, Mike, Spike, and Slug were rounded up for questioning. This time, each one made two statements. None of them made more than one false statement.

Mike:

1. I did not steal the horse.
2. The one who stole the horse is Italian.

Slug:

1. Mike never stole the horse.
2. The one who stole the horse is German.

Spike:

1. I never stole the horse.
2. It was Slug who stole the horse.

Assuming that one of those three men really stole the horse, which one was it?

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

Spike cannot have stolen the horse because he would be issuing two false statements. If Mike stole the horse, then his second statement must be true, namely that the one who stole the horse is Italian. But then Slug would be issuing two false statements as was the case with Spike earlier. Accordingly, Slug stole the horse.