A conservative religious family in western Michigan, whose vast fortunes derive from auto parts and government security contracts, is spending hundreds of thousands of dollars to ban gay marriage in California.

Blackwater CEO Erik Prince, trained to remain cool in the most stressful of situations, was unflappable during his congressional testimony yesterday.

In an appearance before the House Committee on Oversight and Government Reform, he expertly defended his company’s activities in Iraq, where about 1,000 Blackwater guards protect U.S. diplomats and other State Department employees. He described Blackwater as “a team of dedicated professionals” who “risk their lives to protect Americans in harm’s way overseas.”

Prince, a former Navy SEAL, founded Blackwater in 1997. In the early years of operation, the firm did limited business with the U.S. government. However, company fortunes shifted dramatically after the Sept. 11, 2001, terrorist attacks and the onset of war in Iraq. By last year, federal contracts totalled $600 million, primarily from protection services provided to the State Department.

Blackwater USA, the State Department’s largest private security contractor, is under siege on several fronts.

Iraq’s state minister for national security affairs announced today that the firm would face criminal charges for the fatal shootings of Iraqi citizens. Blackwater, based in Moyock, N.C., is also under investigation on the home front.

But a tight web of political and business connections helps shield the company from the most formidable of attacks.