What is Kevin Hiding?

Last week, Mark Vincent Kaplan's former spokesperson, Michael Sands, told X17 he was subpoenaed to be deposed for Britney and Kevin's ongoing custody battle.

As the former media spokesperson for K-Fed's attorney, Michael was apparently privy to a lot of information that Kevin and his lawyer don't want exposed!

Life & Style has obtained a letter from Mark Vincent Kaplan, delivered to Michael Sands, requesting "copies of any documents you [Sands] intend to produce in response to the subpoena so that we may review the documents to determine any appropriate objection and basis for protective order."

So what exactly does Mark Vincent Kaplan have to hide?

An insider tells the mag: "Mark wants all emails, hand written records, notes, meeting notes, phone call notes and records, anything that has to do with his client Kevin Federline, to be handed over. He doesn't want anyone seeing the things that have been said privately, and doesn't want anyone to know about the secret plans and quotes said behind closed doors with regards to Britney."

The source goes on to say, "there are a lot of people that are starting to see that what's going on is not as pretty as it seems. Britney is mentally ill, and Kevin and Mark Vincent Kaplan have been making her look bad, taking her to court, keeping her from the kids."

Click through to read the entire letter.