Federal utility regulators issued a subpoena to El Paso Corp. Chief Executive William A. Wise on Friday requesting documents as part of California's 100-day hunt for evidence of market manipulation during the state's energy crisis of 2000-01.
El Paso spokesman Mel Scott said the Houston company had received the subpoena and was cooperating.
Federal Energy Regulatory Commission Judge H. Peter Young granted the request from the California attorney general's office and other agencies as the state pushes to win $9 billion in refunds for power costs from El Paso and other firms.
Another FERC judge found last month that energy companies overcharged California by $1.8 billion but said the state still owed suppliers $1.2 billion because it had $3 billion in unpaid bills.
The FERC commissioners have not yet ruled on the matter.
In the meantime, California has been rushing to gather evidence of market manipulation as part of a special 100-day discovery period granted state officials by FERC in November on orders from the U.S. 9th Circuit Court of Appeals in San Francisco.
That effort is set to end Feb. 28, said Erik Saltmarsh, acting executive director of the state Electricity Oversight Board, one of the parties to the proceeding.
"It's a discovery battle right now," involving several hundred sets of written requests on more than 100 targets, Saltmarsh said.
"One hundred days is not a very long time in the context of discovery unless the other side is being quite cooperative," he said.