Michael Cantrell, an engineer at the Army Space and Missile Defense Command headquarters in Huntsville, Alabama, along with his deputy, Doug Ennis, had lined up millions of dollars from Congress for defense companies. Now, Cantrell decided, it was time to take a cut.

“The contractors are making a killing,” Cantrell recalled thinking at the meeting, in 2000. “The lobbyists are getting their fees, and the contractors and lobbyists are writing out campaign checks to the politicians. Everybody is making money here - except us.”

Within months, Cantrell began getting personal checks from contractors and later returned to the airport with Ennis to pick up a briefcase stuffed with $75,000. The two men eventually collected more than $1.6 million in kickbacks, through 2007, prompting them to plead guilty this year to corruption charges.

Cantrell readily acknowledges concocting the crime, but what has drawn little scrutiny are his activities leading up to it. Thanks to important allies in Congress, he extracted nearly $350 million for projects the Pentagon did not want, wasting taxpayer money on what would become dead-end ventures.

Recent scandals involving former Representative Randy Cunningham, Republican of California, and the lobbyist Jack Abramoff, both now in prison, provided a glimpse into how special interests manipulate the federal government.

Cantrell’s story, by contrast, pieced together from federal documents and dozens of interviews, is a remarkable account of how a little-known, mid-level Defense Department insider who spent his entire career in Alabama skillfully gamed the system.