Has anyone heard of medicaid and public assistance fraud strike force?

i received a letter in the mail from above named organization stating that some of my personal info was posted on a website accessible to the public but promptly removed when it was discovered. because of this, the organization supposedly purchased CSIdentity for me for 1 yr to monitor credit activity but i have to sign up for it with the PIN # given to me. is this legit? should i be concerned? or is it just someone trying to obtain info from me? i also rec'd in my email recently an email from IRS mailer. wouldn't the IRS contact by US postal mail and not email? please advise.