The departure of several staff attorneys from the US Attorney's office in San Francisco will not hamper its ability to investigate stock options backdating cases, including one involving Apple CEO Steve Jobs, a spokesman said.

Several staff attorneys have left the office, but others have been assigned to take their places, according to spokesman Luke Macaulay. One of the most high profile companies being investigated is Apple, though Macaulay declined to confirm reports on Tuesday that Jobs was interviewed last week by federal prosecutors and officials of the US Securities and Exchange Commission (SEC). Apple did not respond to requests for comment.

Kevin Ryan, the head of the US Attorney's office for the Northern District of California, announced his resignation 16 January, which he said was for personal reasons. His replacement, who would be appointed by the US president, has not yet been named, Macaulay said. Assistant US Attorney Chris Steskal, a member of the Securities Fraud Section in the San Francisco office and a task force focused specifically on options backdating, is leaving to work at a private law firm. But another assistant US Attorney, Tim Crudo, has been added to the task force.

And although attorney Haywood Gilliam left his position as chief of the Securities Fraud Section late last year, attorney Elise Becker has been named acting chief, Macaulay said.

"Government offices typically go through transitions while ensuring stability of cases and investigations. US Attorney Ryan is taking care to ensure a smooth transition in the office's cases," Macaulay said, responding to news reports that the departures may hamper the US Attorney's Office's ability to prosecute cases.

Five attorneys and at least eight FBI agents in the San Francisco office form a task force investigating reports that officials of public companies violated federal rules on accounting for stock options granted to employees, he said.

The former CEO of Brocade Communications Systems, Gregory Reyes and Stephanie Jensen, its former vice president of human resources, are the first executives prosecuted in San Francisco on fraud charges related to alleged backdating. They are scheduled to go on trial later in 2007.