I was actually subpoenaed to be a witness for my best friend's now xh when they were in a messy divorce trial....I called his attorney and told him that he didn't want to put me on the stand because I had nothing complimentary to say about his client, that I knew how he had treated his wife, and I would not help his case. I was never called to the stand.

Could it be that they want him so that he will not testify for the prosecution? This could just be a trick to keep him from hurting their case. At any rate, wouldn't all he could bring to light fall under the category of 'hearsay' and, thus, not really be admissible?