As far as I know, subject-verb inversion involves switching the sentence subject and the verb when another item has to occupy the first position of the sentence. The following is an example from the Wikipedia link:
Under her bed have been found remnants of marijuana consumption twice.
As we see in the example sentence, the verb phrase precedes the subject without changing its internal word order, namely, [have] + [been] + [found].
However, I have seen the following sentence in which the word order inside the verb phrase changed:
Also arrested were eight other suspects who allegedly worked secretly for ETA while maintaining the appearance of normal lives, Rubalcaba said at a nationally-televised news conference in Madrid.1
I expected that the word order should be: Also were arrested ....
I wonder which word order is grammatical in the above sentence.
1 Al Goodman, "Nine ETA Bombing Suspects Arrested." CNN.com, July 22, 2008