In 2006, Los Angeles federal prosecutors were in the middle of a wide-ranging investigation of Rep. Lewis of California, who until January was chairman of the powerful House Appropriations Committee. He remains its senior Republican. The investigation focused on earmarks, or special spending measures, that benefited clients of a now-defunct lobbying firm to which he had close ties.

People with knowledge of the case said that by the time the investigation stalled in December 2006, it had branched out into other areas, including Mr. Lewis's June 2003 role in passing legislation that helped giant hedge fund Cerberus Capital Management. People associated with Cerberus around the same time gave at least $140,000 to a political action committee controlled by Mr. Lewis. Cerberus officials didn't respond to phone calls or emailed questions concerning the Lewis inquiry. ...

After the lead prosecutor in the Lewis case quit, others assigned to the case took time getting up to speed. Brian Hershman, a former deputy chief of the Los Angeles office's public corruption section, declined to comment on specific cases, but confirms that his group's work overall was derailed by the departure of experienced prosecutors. Like several others, he says he left for more money to support his family.

Replacements "are mostly rookies," he says. "It will be some time before they'll be able to restore the section to what it was before."

Rumored AG replacement consideree Theodore Olson is a partner at the firm, Gibson, Dunn, which represents Lewis, and which coincidentally hired the former US Attorney for Los Angeles, Debra Wong Yang, who had been pursuing the Lewis case, which now looks all but dead.