Carol Weidman, 26, was insane when she strangled and stabbed her mother to death last year at their Halawa Heights homes, a judge ruled yesterday.

Circuit Judge Michael Town found Weidman not guilty by reason of insanity and committed her to indefinite confinement and treatment at the Hawaii State Hospital because she is a continuing danger to herself and others, Deputy Prosecuting Attorney Rom Trader said.

Weidman murdered her mother, Lisa Weidman, May 30, 2007, at their Pa'ihi Street home because she was under the "delusional belief that her mother was about to kill her," Trader said.

"Basically, it's a very tragic case with a tragic outcome for the 55-year-old victim, as well as the defendant," Trader said.

The defendant has "a long and sad history" of mental and physical problems that began when she was born without a thyroid, a condition that was undiagnosed for 18 months, said Trader.

Weidman was raised in California by her father but decided to move here last year to spend time with her mother, from whom she had lived apart for years, Trader said.

Lisa Weidman, who was known as Lisa Wu, "wasn't really aware of the extent of her (daughter's) problems," said the prosecutor.

Carol Weidman "arrived here in April 2007 and six weeks later she had spiraled into a deep depression" and was suffering from delusions and psychosis, he said.

An independent panel of three mental health experts, as well as a fourth expert retained by the defense, examined Weidman and told Town that although she was fit to stand trial, she was insane at the time of the offense.

Weidman has been diagnosed as mildly retarded and "there is some indication that she is an undiagnosed schizophrenic as well," said Trader.

She will be "confined at the State Hospital for the foreseeable future," he said.

If Weidman's condition improves "at some point down the line," he said, additional hearings would be held to determine if she is eligible for release from the institution.