Secretary John McHugh said Friday during a visit to the post that it is a critically important issue for the Army. He called the matter a "frustrating mystery."
The Army said earlier this week that tests on building materials and the air inside homes found nothing that could have contributed to the deaths. The investigation is ongoing, and McHugh said he wants to look at virtually every possible environmental factor.
About 45,000 people live at Fort Bragg, including about 6,200 families.