Late on the morning of Jan. 3, Kathleen McCourt Householder, with her 2-year-old son Dustin in tow, appeared at the IGA supermarket on the east side of Winchester, Va., cashed a check, bought cigarettes and left. A minute or so later, she was back.

"She said, 'Will you help me? My baby's gone,' " said IGA employe Jeannie Miller. " 'Will you call the police?' "

Miller called authorities and went to the parking lot to help look for the baby girl Kathleen Householder said she had left in her pickup truck. "She was calm, not crying, not panicked," Miller said.

The phone call touched off a major hunt for the 2-week-old infant, and Kathleen Householder appeared several times on Washington area television newscasts, crying and pleading for her baby's safety.

Eighteen days later, as public sympathy turned to shock and anger, Kathleen Householder, 21, of Rippon, W.Va., was arrested by West Virginia state police and charged with first-degree murder in her infant daughter's death.

Now, all sides have been left to ponder how an attractive, intelligent young woman got herself from a middle-class home in Florida to the Jefferson County jail here, held without bond and possibly facing life in prison.

Kathleen Householder gave birth to her daughter, Lindsey Blake Householder, on Dec. 17 at Winchester Medical Center. The baby died 17 days later.

She told police several versions of how Lindsey had died accidentally at home near Rippon, about 10 miles south of Charles Town. But, according to prosecution testimony, police believed the account she gave Jan. 21. In that instance she said that, frustrated because both children were crying, she threw a rock at the open door of the couple's Ford truck and struck the baby, who was lying in an infant seat in the cab.

"Dustin had fallen down and was crying," said Steven M. Askin, Householder's defense attorney. "They'd been crying all morning. She assumes she hit the baby with the rock because the infant seat fell over."

According to police, Kathleen Householder went to her kitchen for a plastic trash bag and placed Lindsey inside. With Dustin beside her, she drove north on Rte. 340 through Charles Town and across the Potomac into Maryland, then turned and retraced her route.

With Lindsey in the bag on the truck's flatbed, she drove south into Virginia. She told police she threw the bag into the Shenandoah River near where it flows under Rte. 50, south of Berryville.

Of the rock-throwing incident, Kathleen Householder allegedly told West Virginia state police: "It was my fault . . . . I didn't mean to."

Kathleen Householder's rural life style about five miles east of tiny Rippon appears to be far different from that where she grew up as the only child of a middle-class couple in Orlando, Fla.

Kathleen McCourt attended two private Catholic schools, then spent three years at Edgewater High, one of the city's six public schools. She graduated June 11, 1982.

"She was a beautiful girl," a neighbor told the Orlando Sentinel. The woman, who said she had known Kathleen since she was 5, described her as a bright student who got good grades and was a good swimmer.

Kathleen's father, James McCourt, a bank official, died a few years ago. Her mother Joyce, an employe of the Florida state probation and parole service, declined to be interviewed by The Washington Post.

According to friends, Kathleen met her future husband, Daniel Householder, now 25, in 1980 while she was a student in Orlando. Daniel Householder, the youngest of eight children raised in this area, was in Florida with one of his brothers seeking construction jobs. In 1982, to the surprise of some of their friends, Kathleen and Danny moved back to Rippon.

"Orlando's kind of a big city, and we were all kind of surprised that she wanted to live a country-style life," one friend, John Zawodnik, told the Winchester Star. "All she ever knew was Orlando."

For about two years, the house that the couple rented on the bank of the Shenandoah, east of Rippon, had no indoor plumbing, and Kathleen hauled water from the river for washing. Surrounded by the natural beauty of the Blue Ridge and the river, the setting is remote, and difficult in winter.

The couple seemed relatively well off financially. In court papers filed in Charles Town five weeks ago, Kathleen Householder listed her husband's income as a carpenter as $1,600 per month. She said she earned $360 a month as a part-time employe at the Winchester Medical Center, working in the maternity ward. She listed debts totaling $5,800, the largest of which is a $4,000 truck loan.

But there were other difficulties. On March 8, about 3:30 p.m., Daniel Householder was involved in a collision with another car on Rte. 9 east of Charles Town. The other driver, Gary Lewis Brooks, died. A sheriff's deputy at the scene alleged that Danny had been speeding, driving left of the center line, and was drunk.

"He could barely talk," the deputy reported.

Daniel Householder was indicted by a Jefferson County grand jury in April on charges of drunk driving resulting in death, casting a cloud of uncertainty over the couple's future. The charges are still pending.

According to defense lawyer Askin, who also represents Daniel Householder, Danny's driver's license was suspended last year following a series of speeding tickets and unpaid fines in Virginia as he commuted to and from his job in Washington. He now rides with another driver, Askin said.

Finally, in November, a month before Kathleen Householder was due to deliver, flooding of the Shenandoah swamped the Householders' house and forced them out until repairs could be made. "They lost everything downstairs . . . and had to put new floors down," said Anthony Householder, Daniel's brother.

All of those events were prelude to whatever happened two days after New Year's.

According to Askin, Kathleen's mother visited when Lindsey was born but returned to Florida "a couple days" before Jan. 3, when Kathleen Householder reported her baby missing from her parked pickup.

"We had no evidence at the start to dispute the story," said Winchester police Capt. Ralph G. Hite, who headed the investigation. "But there were some things that made us a little bit suspicious."

The infant seat and a neatly folded baby blanket were still in the truck, which struck investigators as odd, Hite said. And they located a witness who was near the truck in the shopping center parking lot the entire time but had seen nothing suspicious.

Furthermore, a $15,000 reward offered by the Maryland-based National Missing Child Search Society failed to turn up any leads. "Our Crimesolvers program here offers $1,000, and we've had relatives turn in relatives for that much money," Hite said.

While treating the case publicly as an abduction, police -- with a national missing child organization's encouragement -- decided to ask Kathleen Householder to undergo a polygraph, or lie detector, test. She agreed.

"It's one of the more fragile parts of the business," said Jay Howell, executive director of the Washington-based National Center for Missing and Exploited Children. "It's not a popular or easily understood part of the process. But it's a base that needs to be covered in order to remove the parents as suspects . . . especially when a child disappears while in the custody of a parent."

On Jan. 20 -- with reports of possible sightings of Lindsey coming in from as far away as Louisiana and Florida -- Hite and a second investigator drove Kathleen Householder to the Maryland Institute of Criminal Justice in Millersville, Md., near Baltimore, for the polygraph.

Hite, who was trained in polygraph techniques, said he thought that "it might be better" if the test was conducted by an impartial party there.

"Our issue at that point was, was the baby ever in Winchester on Jan. 3 , was it stolen from Winchester?" Hite said. He declined to divulge the results of the examination, but on the way home, the officers dropped Kathleen Householder off at the West Virginia state police barracks in Charles Town for a talk. She gave police a written statement before going home.

The next morning, Askin said, state police took Kathleen Householder in for further questioning. In her statement, she agreed to lead police to the spot where the trash bag had been left.

Searchers found the bag containing the body about 100 yards away.

Later that day, between 5 and 7 p.m., Kathleen Householder underwent a second polygraph and allegedly told police that she had unintentionally struck the baby with a rock.

A polygraph administered the same evening to Danny Householder indicated, according to Askin, that he had believed the kidnap story and had been unaware for the previous 17 days that the baby was dead.

Kathleen Householder was placed under arrest.

Under a special court order, she was allowed to return to Virginia on Jan. 27 for Lindsey's funeral. Daniel Householder, his arm around his wife, helped her back into the police car.

Askin said he plans to file court papers this week asking that Kathleen Householder be freed on bond pending the outcome of the case. "The evidence doesn't come anywhere close to a murder case," said Askin, arguing that police work in the case was marred by violations of his client's rights.

Askin said he is also pursuing postpartum syndrome in the young, troubled mother as a line of legal defense.

"I don't believe she did it on purpose," Daniel's brother Anthony said. "I really don't know what happened. I'd like to know. But she's the only one who knows."