A woman sought for the slayings of her daughters in California nine years ago has been arrested in Salt Lake City.

Theresa Jimmie Knorr, 47, was arrested Wednesday night by two Placer County, Calif., detectives with the assistance of a Salt Lake police officer, Placer County Sheriff Donald J. Nunes said.Knorr and her sons, William Robert Knorr, 26, and Robert Wallace Knorr, 24, were charged last week after a Utah woman, a daughter of Theresa Knorr, contacted authorities.

Nunes said Placer County detectives flew to Salt Lake City after learning of a possible address of the mother. They staked out the address, a post office box where there was uncollected mail and an address where Knorr cared for an 86-year-old woman.

Knorr, who had been using the alias of Cross, was arrested without incident at 5:15 p.m. and booked into the Salt Lake County Jail. It was not known whether she would fight extradition.

Nunes said it was believed she had been in Utah since 1988.

According to police, she obtained a Utah driver's license in 1992 under the name "Teresa Jimmie Cross" and had been living at an address in Bountiful.

Salt Lake Police Sgt. Don Bell said she apparently had moved recently, though, and that police obtained a forwarding address in Salt Lake.

Nunes earlier called the case "one of the most bizarre and unbelievably sad family situations anyone could ever imagine."

Suesan Knorr was murdered in July 1984. The 17-year-old was doused with gasoline and burned alive near Squaw Valley.

Her half-sister, Shelia Gay Sanders, 20, was starved to death while imprisoned in a closet in a Sacramento apartment. Her body was found in a cardboard box near Truckee.

Nunes said Placer County detective John Fitzgerald received a call Oct. 28 from the daughter in Utah. Fitzgerald and Inspector Johnnie Smith - the officers who made the arrest Wednesday - traveled out of state to further interview the daughter the next day.

A statement released by the sheriff said the Utah woman "had tried to tell the story to other officers and an attorney, who apparently all deemed the information implausible. In frustration, she obtained a map to locate the appropriate jurisdiction, which resulted in the call to Fitzgerald."

The woman told reporters said she was 13 when the slayings occurred and that she ran away three years later.

She told officers the mother, Theresa Jimmie Knorr, shot Suesan Knorr in the chest after an altercation in early 1984. The girl survived but the bullet lodged in her back.

The mother became worried because her daughter had previously reported abuse in the family and decided to surgically remove the slug herself, officers were told.

During the "surgery," Suesan Knorr's condition deteriorated and the mother allegedly summoned her sons to kill the teenager and dispose of her body. It was found by a motorist near Squaw Creek near the entrance to Squaw Valley in the early morning hours of July 17.

Nunes said cuts and possible stab wounds found on the body were no doubt a result of the crude operation.

Sanders also apparently had a disagreement with Theresa Knorr. Sanders allegedly was beaten and locked in a 2-foot-square closet and denied food and water until she died. Again, the sons were allegedly summoned to dispose of the body.

A complaint filed last Thursday charged Knorr and her sons with murder and conspiracy to commit murder in the deaths of Suesan Knorr and Sanders.

William Robert Knorr was arrested Friday in Woodland. Robert Wallace Knorr was in custody in Ely, Nev., on unrelated murder charges.