Lawyers for former Brocade Communications CEO Greg Reyes are working overtime to prevent their client from being the first casualty of the burgeoning federal investigation into backdating stock options. CNBC has learned that just last Thursday they made a detailed power-point presentation to the US Attorney’s Office in the Northern District of California which laid out key points in their defense, including their contention that Reyes didn't personally benefit from the backdating and their opinion that Reyes is "a good guy."

As CNBC was first to report, Reyes is likely to face civil charges by the Securities and Exchange Commission in its investigation of stock-options back dating. The SEC's enforcement division has issued a Wells Notice to Reyes informing him that the staff has recommended to the full commission that he should be charged in the matter. While the full commission may decide not to bring charges, such moves are rare, and even attorneys for Reyes concede that the SEC will likely file a civil case in days or weeks.

The big question is whether Reyes, who resigned from Brocade more than a year ago, will be charged criminally by the US Attorney's office. Lawyers and representatives for Reyes say that last week they made a last-ditch attempt to get prosecutors to back off during a lengthy power-point presentation made to the US Attorney in San Francisco. According to people with direct knowledge of the presentation, Reyes' lawyers argued that he had little accounting knowledge - he was predominantly a salesman, and even though he had control over the granting of options, Reyes wasn’t conscious of the fact that he was doing something potentially illegal. Further, his attorneys claimed that Reyes relied on the accounting expertise of the company’s CFO and audit committee to serve as a check in his options granting practices.