MOUNT VERNON — Larry Williams testified Tuesday he felt “responsible” and “ashamed” after five weeks of hearing people testify about allegations he and his wife abused their adopted children.

He said he sometimes disagreed with wife Carri Williams’ ideas for discipline and regrets not intervening.

“I’m the dad,” he said. “My daughter died. … Possibly I could have done something to stop it, but I didn’t.”

Larry and Carri Williams are charged with homicide by abuse and first-degree manslaughter in the death of Hana Williams, who collapsed in the family’s backyard in May 2011 and died of hypothermia hastened by malnutrition. They also are charged with first-degree assault of the boy they adopted from Ethiopia at the same time as Hana.

Unlimited Digital Access. $1 for 4 weeks.

Tuesday was the first time either defendant took the stand. Larry Williams described his long work hours at Boeing and said he did not know the extent of what was going on while he was gone.

The night Hana died, Larry Williams didn’t know how long she’d been outside, whether she’d eaten or whether she’d been spanked, he said. When his wife called to say Hana had collapsed, he told her to call 911, he said.

“(I wanted) to get home as quick as possible. Screaming, ‘No!’ all the way home. Praying,” he said, sniffing and sighing.

He said he did not remember telling his wife, “Oh, great, that again,” or saying he was not surprised when she told him the girl was stumbling around the backyard falling down.

Larry Williams said he had not noticed Hana’s 30-pound weight loss leading up to her death and was “struck” by how thin she was when he saw her unconscious, naked body that night.

He said he had filled out paperwork to change Hana’s birth certificate in 2010 after she told him she was 16 rather than 13. That change was never approved.

Hana’s age is key to the case because the homicide-by-abuse charge applies only if she was younger than 16 when she died. Various experts who saw her body have not been able to place her age definitively.

As lawyers on both sides enumerated various discipline tactics used on Hana — shaving her head, having her shower with a hose outside, making her use a portable toilet instead of the family bathroom, locking her in a closet — Larry Williams often said they were his wife’s ideas, or that he didn’t approve but didn’t stop them.

Some punishments, such as spankings, cold showers for pants-wetting, having the adopted children eat outside or serving them cold leftovers or frozen food, Larry Williams said he participated in but did not know how much they happened when he wasn’t around.

The oldest biological Williams son, Joshua, testified Tuesday that he heard his parents argue about their discipline of the adopted children, and that the frequency and severity of that discipline increased.

Joshua Williams was granted immunity for his testimony.

The Williamses had seven biological children before adopting two more from Ethiopia in 2008.

As the two settled into the Williams home and behavior problems emerged, the Williamses employed the same discipline tactic they used on their other children: spanking with a piece of plastic plumbing line they called a switch.

Larry Williams testified he stopped spanking his adopted children in early 2011 because he wanted to try a different discipline strategy. He argued with his wife about this, but nothing changed, he said.