Kia Johnson, a sweet, book-smart 18-year-old, was eagerly anticipating the arrival of her baby boy, due July 30. She'd already had some sporadic contractions, relatives said, and baby shower gifts filled her apartment.

But she disappeared Tuesday after a visit to see the baby's father at the Allegheny County Jail. And none of her family saw her again until Friday.

By then, Ms. Johnson was dead, her hands and feet bound, plastic over her head and her uterus sliced open, a placenta near her body.

Hours before officials identified Ms. Johnson as the slain teenager found face down in a reeking, fly-filled Wilkinsburg apartment, her panicked family members had arrived at a theory of how the "innocent, naive" McKeesport girl could have met such a horrific end. They think she befriended suspect Andrea Curry-Demus at the jail, where the suspect also went to visit her husband, Raymond Demus, who is incarcerated there for rape.

Yesterday, Allegheny County police came to the same conclusion.

Ms. Curry-Demus, 37, was charged with homicide, four days after she showed up at West Penn Hospital claiming she had just given birth to a newborn boy, his umbilical cord still attached. Medical officials determined she had not.

The victim's cousin, Tereka Nesbit, said yesterday that Ms. Johnson told an aunt about two weeks before she went missing that she "was cool with" a couple of women she'd met in the jail's visiting area and she had gone to their homes to hang out after a jail visit.

"There's no question she's trusting," said Ms. Nesbit, 33, of McKeesport. "She was so kind and sweet. A grown man wouldn't have been able to [lure] her, but a friendly woman would. She would have been thrilled to talk to anybody about [her] baby."

Ms. Johnson had been an "extremely good" student at McKeesport Area Senior High School, "which is probably why I was surprised she got pregnant," Ms. Nesbit said. However, relatives quickly rallied around her after learning she was expecting, and they were delighted that Ms. Johnson, the second of four siblings, would be delivering.

The young woman grew up at the home of her paternal grandmother, Marie Foster, where her father, Eric Johnson, and siblings also lived.

Ms. Johnson's mother, who relatives said lives in Virginia, traveled to McKeesport for her daughter's baby shower a couple months ago. Her mother was preparing to move back so she could be nearby to help with the baby, relatives said.

"She came back from the baby shower planning to be a grandmother and now she's [here in McKeesport] planning a funeral," Ms. Nesbit said.

Lots of relatives in the large, close-knit family talked about going to visit her in the hospital when she delivered.

They were less thrilled about the baby's father. Court records indicate that Ms. Johnson's steady boyfriend, Terrell D. Barnes, 19, of Mc-Keesport, has been lodged at the jail since March 24 on two dozen charges from four separate incidents. The charges against Mr. Barnes, who also uses the name Terrel, range from burglary, aggravated assault and reckless endangerment to false imprisonment, possession of a firearm and terroristic threats. According to the records, the offenses occurred in February, March and May.

Ms. Johnson had gone to visit him "every chance she got," more than once a week, Ms. Nesbit said.

When their pregnant cousin didn't return home after a jail visit Tuesday, her cousins went to the apartment where she lived alone in Crawford Village and found nothing out of place. They canvassed Crawford Village, but nobody knew anything.

"The entire Crawford Village is mourning for us" now, Ms. Nesbit said, "Everybody knew we'd been looking for her."

One cousin then checked with officials at the jail who confirmed she had visited Mr. Barnes Tuesday morning, but the cousin wasn't able to inquire with Mr. Barnes directly because she didn't know his correctional identification number. They had to sit out a 24-hour waiting period to file a missing person's report with McKeesport police.

Knowing that Ms. Johnson had already had some contractions and had recently joked that she didn't think she'd make it to her due date, relatives checked at Magee-Womens Hospital and other hospitals to no avail. When they heard news reports about a woman arriving at West Penn with a newborn, and later telling police she'd bought the child from a pregnant woman, they became suspicious.

The suspect, Ms. Curry-Demus was initially arrested on charges of child endangerment. Early yesterday, county police added charges of homicide, kidnapping and unlawful restraint. The child remains under observation at West Penn Hospital.

Early Friday afternoon, six female cousins and aunts piled into a car for Wilkinsburg when they heard reports that county police were looking for a body at Ms. Curry-Demus' apartment. They encountered relatives of another missing pregnant woman in the crowd.

When officials from the medical examiner carried out the body 41/2 hours later, one cousin thought it could be Ms. Johnson -- who was 5 feet 1 inch tall and weighed about 115 pounds -- based on how slight the body looked on the gurney.

Ms. Johnson's father released her dental records, and in less than a day, officials confirmed the family's worst fears.

Yesterday afternoon, family members gathered at an aunt's house in McKeesport to begin to process what happened. Relatives have not yet announced funeral plans, or what is to become of the baby.

"It's unfathomable. What's hardest for me is that she was alive when this happened," Ms. Nesbit said. "She suffered so much. We're sick about this. It didn't help for the news to confirm what we were already thinking."