OSAKA -- A woman pleaded guilty in court Tuesday to restraining her ailing husband in a dog collar outside their Osaka home, causing him to choke to death.

In the opening session of her trial before the Osaka District Court, Tokuko Wakamatsu of Yodogawa Ward admitted to charges that she killed her husband, Mutsuo, 53, on Dec. 5.

"That is correct," Wakamatsu, 53, said in response to the prosecution statement.

Wakamatsu was accused of turning violent against her husband, who suffered a stroke a few years previously and suffered speaking difficulties and incontinence.

She initially just yelled at her husband, but then turned to violence, prosecutors said.

Several days before the fatal incident, Wakamatsu used a chain to tie her husband to a post on their veranda, but he managed to escape.

That prompted her to "make sure he would not escape again," the prosecution's statement said.

On Dec. 5, she wrapped a dog collar and meter-long chain twice around his neck, tied it to a lamppost in front of the house and tied his hands with a rope behind his back, prosecutors said.

The chain was wrapped so tightly that it suffocated him, they said.