McGuire's findings come after three months spent reviewing records of Army suicides, talking to soldiers and commanders and visiting installations throughout the country, she said.
The Army reported a record 143 suicides among active-duty soldiers last year, the highest since statistics were first kept in 1980. Suicides this year are on track to break last year's record, Army statistics show.
Most suspected suicides are later confirmed as suicides, records show.
Risk-taking is common among soldiers who are suicidal. Such behaviors include sleep deprivation, erratic conduct, excessive alcohol use and abuse, violations of Army regulations, high-risk driving, mishandling finances and infidelity, McGuire says.
These behaviors can further aggravate existing mental health problems, creating a downward spiral that can end in suicide, McGuire says.
Along with soldiers who engage in risky behaviors, McGuire says, the Army has a greater number of troops who entered the service with pre-existing anxiety or depression or who have stopped taking their behavioral medication in order to meet entrance requirements.
Managing soldiers at home is different than in combat, McGuire says. Often, commanders can lead troops in battle but lack the skills to monitor troops closely at home.
The Army's failure to police risky behaviors has made it harder to identify and seek help for the smaller numbers of soldiers who may be suicidal, she says. "(It's) talking to soldiers. 'Who's the loner? Who's isolated? What are you guys doing this weekend?' " McGuire says.
About two-thirds of suicides occurred in or around installations, Army statistics show. Half are among combat veterans. The other half are soldiers who never deployed. About one-third of suicides occurred in either Iraq or Afghanistan.
Army officials acknowledge that classes in how to manage troops at home get pushed back to accommodate combat training.
In the past year, 7,600 staff sergeants promoted to sergeant 1st class were allowed to postpone such classes for up to 270 days, says Lt. Col. Mike Moose, an Army spokesman.
Improved garrison supervision may go only so far, says David Rudd, dean of the College of Social and Behavioral Science at the University of Utah, a leading authority on civilian and military suicides.
The longer the wars in Iraq and Afghanistan continue, Rudd says, the more likely it is that soldiers who have seen combat will kill themselves. Also, young men, in the military and civilian life, are often reluctant to seek help, he says.
"There's only so many things you can do and then it becomes the responsibility of the individual" (to receive counseling), he says.