Coast Capital Financial Services is trying to rip off my 98 year old mother-in-law Los Angeles California

My 98 yo mother in law received an "official" notice that she is a 2nd prize winner in the second cateogry of the USA Mega (under the international Sweepstake) draw held on July 10, 2013.  Enclosed in the envelope, which has no return addree, but airmail stamps, was also a check from the Silicon Valley Bank, 3003 Tasman Dr, Santa Clara, CA 95054 from a company called Cognoptix, Inc, 20 Main Street, Acton, MA 01720, www.cognoptix.com/about/about.htm. 

I've left a message at cognoptix for a call back.  Check is made out to my mother in law in the amount of $4,650.00.  Letter states that there is a processing fee of $3850.00 and that her prize is $355,000.00.  She is advised to contact her claim agent, Allen Nelson at the number given above for Coast Capital.  It is signed by Sarah martins (like that, no upper case M on Martins), Promotion Manager. (with a period after Manager).  I called last night and a gentleman with a foreign (not American/English) accent answered, when I asked him what company is this, he hung up. Tried calling this morning and there is a message that this number is currently unavailable.

I photocopies the check and all of a sudden watermarks saying VOID were apparent, appearing all over the check. I am calling Silicon Valley Bank as soon as they open to alert them as well.