At the center of Enron Corp.’s web of finances sits LJM2 Co-Investment LP — a secretive entity hatched by Enron’s former chief financial officer. Until last month, it was run by Michael Kopper, the energy company’s one-time managing director for North America.

Enron’s dealings with LJM2 and other partnerships have been the subject of scathing criticism from Congress and a more restrained, if equally damning, assessment in a recent report for a committee of Enron’s board.