It has been more than 18 years since Andrea Curry-Demus first tried to kidnap a baby that wasn't her own.

She spent almost half that time in jail. Then she spent years wrestling with mental health problems, turbulent romantic relationships and a shoplifting habit.

Now Ms. Curry-Demus, 38, of Wilkinsburg is facing homicide charges after police on Friday found the body of 18-year-old Kia Johnson in her apartment. The girl's abdomen and uterus were sliced open, her hands and feet bound by duct tape, her head covered in plastic and her body wrapped in a comforter and garbage bags.

On Wednesday, Ms. Curry-Demus had shown up at West Penn Hospital with a newborn baby, falsely claiming to be the mother. Police arrested her the following day.

"It is just a sad state of affairs," said Kevin Flaherty, who, as a court-appointed attorney, defended Ms. Curry-Demus in 1990.

In May of that year, when she was 20 years old and living in Garfield, Ms. Curry-Demus tried to stab a Wilkinsburg woman in an alleged plot to steal her infant.

The next day, Ms. Curry-Demus abducted a different baby, 3-week-old Shaquala Coleman of Highland Park, from a room in Children's Hospital. A few hours later police found Ms. Curry-Demus at her home with the child, who was fine.

"I don't recall that she actually understood the ramifications of what she was doing," said Mr. Flaherty, now the Butler County public defender.

He described Ms. Curry-Demus as "mentally slow."

From 1991 to 1998, Ms. Curry-Demus was imprisoned at SCI-Muncy in Lycoming County. She was released on Aug 31, 1998, but she was placed on probation until 2011.

She lived off welfare and eventually started receiving Supplemental Security Income benefits because of her poor mental health, according to court records. She moved frequently, living at several addresses in Homewood.

In 2002, Ms. Curry-Demus filed for an emergency protection from abuse order against a boyfriend, Leonard Brown. But police later arrested her for assaulting Mr. Brown. He eventually dropped the charges.

Two years later, Ms. Curry-Demus had a brief relationship with James Hammonds, who had fled from a state Department of Corrections "pre-release" placement. He was arrested at her home and taken back to jail.

During this period she tried to care for two nieces. One girl, however, repeatedly caused trouble in school and the neighborhood, and Allegheny County's Office of Children, Youth and Families took custody of her.

In January 2004, Ms. Curry-Demus was caught stealing several leather jackets worth $575 from the Monroeville Mall. She then lied and told a police officer she was her sister, Brooke Curry.

Two years later, surveillance cameras at the Marshalls clothing store in the Northway Mall caught her ripping security tags off purses and stuffing the purses into larger bags. Two other people were arrested with her.

She received another three years of probation, and court records say she agreed to seek treatment for mental health, drug and alcohol problems, take medication prescribed by a psychiatrist and meet monthly with her probation officer.

Last year, Ms. Curry-Demus married Raymond Demus. He was arrested in June on charges of raping the daughter of his ex-girlfriend.

Ms. Curry-Demus went to visit her husband at the Allegheny County Jail last Tuesday. That apparently was when she met a pregnant Kia Johnson of McKeesport, who was also at the jail to visit her boyfriend, Terrell Barnes.

Surveillance cameras at the jail captured footage of the two women chatting, according to a criminal complaint filed this weekend against Ms. Curry-Demus. Ms. Johnson was wearing a white long-sleeve hooded sweatshirt over a red and white striped shirt. The same clothes were on her body when she was discovered at Ms. Curry-Demus' apartment three days later.

Several weeks before, friends and relatives had hosted a baby shower for Ms. Curry-Demus, who had told everyone she was pregnant.

On Friday, she told county police homicide detectives that "two other individuals" brought a "dark-skinned pregnant black female" to her apartment on Tuesday evening, the complaint said. The next morning, the baby "was removed" from the female's stomach and given to Ms. Curry-Demus.

She claimed that she had never met Ms. Johnson before.

According to the complaint, Ms. Curry's sister, Brooke Curry, told police that she went to Ms. Curry-Demus' apartment twice on Wednesday morning, and her sister was the only person she saw there.

The first time, Ms. Curry-Demus repeatedly went into her bedroom by herself and closed the door. The second time Ms. Brooke visited the apartment, Ms. Curry-Demus came out of her bedroom with a newborn she said she had just delivered.

Brooke Curry called for an ambulance and Ms. Curry-Demus was taken to the hospital.

In the meantime, Ms. Johnson's relatives had been trying to find the teenager, who had never returned from her trip to the jail. They filed a missing person report with McKeesport police.

Ms. Johnson's mother, Darlene Lee, who lives in Washington, D.C., said she never considered that something terrible had happened to her daughter.

"My last thought was that they would find her the way she was," she said.

Ms. Johnson was raised in the home of her paternal grandmother, and she lived in Washington briefly last year.

Ms. Lee came to McKeesport with another daughter on Friday, just as county homicide detectives were examining the decomposing body in Ms. Curry-Demus' apartment.

That night, Detective Lawrence Carpico of the county police met Ms. Lee at the McKeesport police station. He told her that her daughter was dead.

The Allegheny County medical examiner's office is still awaiting toxicology results from an autopsy to see if Ms. Johnson had been drugged.

Ms. Curry-Demus is being held at the Allegheny County Jail without bail. No preliminary hearing has been scheduled.

"It's like it's not really happening to me," Ms. Lee said yesterday in a phone interview from a relative's house in McKeesport.

As she spoke, her daughter's picture appeared on a television news report. Ms. Lee started to cry.

"I know a lot of people have me in their prayers," she said.

Lasha Johnson, 19, said yesterday that when she last spoke to her younger sister about a week ago, she did not mention meeting Ms. Curry-Demus or indicate she feared for her safety.

"I asked her who she was talking to, and she was telling me, 'Nobody,' " Lasha Johnson said. "She was stressing, trying to get ready for the baby. She wanted everything to be right when he came."

Ms. Lee has four other children, and she has yet to see her first grandchild, who is still at West Penn Hospital.

The baby boy had a low heart rate when he was first brought in, but he has since recovered.

Ms. Lee said family members planned to name him Kian Terrell Johnson, in memory of his mother.

A memorial fund for Ms. Johnson has been set up at PNC Bank, 560 Lysle Blvd., McKeesport. Funeral arrangements for Ms. Johnson are pending.