Michael Kopper is the first former Enron executive to fall in the federal government's criminal investigation into the collapse of the giant energy-trading firm. He probably won't be the last. Kopper's plea agreement with prosecutors all but names Andrew Fastow, Enron's former chief financial officer, as co-conspirator. And the plea deal also implicates other lesser-known former Enron employees as taking part in a five-year scheme to use a series of private partnerships to defraud Enron and its shareholders of at least $30 million. Even though Fastow and the other employees haven't been charged with a crime, prosecutors are moving to seize some of their assets, including Fastow's Houston home and some $20 million in various bank accounts controlled by Fastow and his family.