Paying Alimony and Child support - but ex has undeclared income !!

My divorce went thru this Feb 2005.
Separation since August 2004, Settlement Agrrement signed in Dec2004.
My ex-wife had started claiming unemployment since earlier that year.

Now per the settlement I am paying her Alimony and Child support of
nearly half the amount of my take home pay. Paid all arrears since
separation Aug 2004 till date.

Now the issue is she is working and always has been working (!) with
some cash only commission only etc deals I guess , since I know that
she is working or is busy fulltime doing Event Management , TV shows ,
MEdia Sales etc .
But all of these are with some of her friend's companies mainly Indian
entrepreneurs or businesses. She is Indian too.

Of late she is also selling real estate in India to the non resident
indians here , getting commission. But these incomes are all UNDECLARED
I would guess.

I am thinking of hiring a lawyer and asking for investigation or
whatever it entails , but just checking here if anyone has any ideas
comments on such an issue ??