The federal task force investigating stock options accounting missteps at Silicon Valley firms, including Apple, has lost another team member.

The lead Attorney in the case Kevin Ryan quit his post last week. This weekend it emerged that lead prosecutor Christopher Steskal is leaving his job to join law firm Fenwick and West.

The news was confirmed by Bloomberg News last Friday. Steskal was also lead prosecutor in the government's case against Brocade CEO Gregory Reyes.

Steskal is the second of five assistant US attorneys on the task force to quit the team since it was created in July 2006.