Karilyn Bales told a morning TV talk show she doesn't feel like she'll ever believe her husband, Staff Sgt. Robert Bales, was involved in the killings.
She also said he showed no signs of post-traumatic stress disorder before he was deployed to Afghanistan. She defended her husband in a weekend interview with NBC's Matt Lauer that aired on Monday.
Bales was formally charged Friday with 17 counts of premeditated murder and other crimes and is being held at a U.S. military prison at Fort Leavenworth, Kan. Officials say Bales left his base March 11 in southern Afghanistan and killed eight Afghan adults and nine children.
Investigators say they believe Bales killed in two episodes, returning to his base after the first attack and later slipping away to kill again. He is reported to have surrendered without a struggle.
Bales, a 38-year-old father of two from Lake Tapps, Wash., was on his fourth tour of duty, having served three tours in Iraq, where he suffered head and foot injuries.
The Associated Press contributed to this report.