That operation moved everything from AK-47s, armored vehicles and plastic explosives to boots and Army uniforms, according to officials who were involved in it. Her former colleagues recall Colonel Selph as a courageous officer who was willing to take substantial personal risks to carry out her mission and was unfailingly loyal to General Petraeus and his directives to move quickly in setting up the logistics operation.

“She was kind of like the Pony Express of the Iraqi security forces,” said Victoria Wayne, who was then deputy director of logistics for the overall Iraqi reconstruction program.

Still, Colonel Selph also ran into serious problems with a company she oversaw that failed to live up to a contract it had signed to carry out part of that logistics mission.

It is not clear exactly what Colonel Selph is being investigated for. Colonel Selph, reached by telephone twice on Monday, said she would speak to reporters later but did not answer further messages left for her.

The enormous expenditures of American and Iraqi money on the Iraq reconstruction program, at least $40 billion over all, have been criticized for reasons that go well beyond the corruption cases that have been uncovered so far. Weak oversight, poor planning and seemingly endless security problems have contributed to many of the program’s failures.

The investigation into contracts for matériel to Iraqi soldiers and police officers is part of an even larger series of criminal cases. As of Aug. 23, there were a total of 73 criminal investigations related to contract fraud in Iraq, Kuwait and Afghanistan, Col. Dan Baggio, an Army spokesman said Monday. Twenty civilians and military personnel have been charged in federal court as a result of the inquiries, he said. The inquiries involve contracts valued at more than $5 billion, and Colonel Baggio said the charges so far involve more than $15 million in bribes.

Just last week, an Army major, his wife and his sister were indicted on charges that they accepted up to $9.6 million in bribes for Defense Department contracts in Iraq and Kuwait.