An Alexandria Woman charged with kidnaping a friend's two children lost a child of her own last March because of sudden infant death syndrome, commonly called crib death, according to people who knew her.

Penny Harris Norton, 35, of 7 W. Caton St., Alexandria, is being held in Alabama on a charge that she kidnaped twin daughters of a friend last weekend -- one from Alexandria and the other from Burlington, N.C. -- and then look them on an automobile odyssey headed for Texas, police in Virginia and Alabama said yesterday.

Also charged by Alexandria police with abduction is Stephen Paul Simeroth, 19, 7723 Heritage Dr., Annandale, also listed as a resident of the Caton Street address.

The nine-year old twins they allegedly abducted, Kathy and Betty Potts, were being cared for yesterday by authorities in Alexander City, Ala., officials said. The children had not been harmed, according to Tallapoosa County, Ala., social worker Becky Turner. Three of Norton's own children were also being cared for by the, Alabama authorities.

Alexandria police said the Potts chidren's mother, Wanda Smith, and their father, who live at 6902 Edgebrook Dr., Springfield, Va., were on their way to Alabama yesterday to claim the two girls.

Police said Norton and Simeroth are being held in Alabama without bond pending an attempt to extradite them to Alexandria.

"It's one of the most unusual cases I've ever worked on," said Alexandria police Sgt. Ron Uhrig yesterday.

Norton and an infant daughter lived for several months this spring at Christ House, in Alexandria, a private, nonprofit charitable organization run by area Catholic churches, an official there said.

Last March the child died unexpectedly from sudden infant death syndrome, a fatal illness whose cause is unknown. The illness annually kills 10,000 children less than one year of age, according to federal officials.

Shortly after the child's death, Norton rented the two-bedroom frame house on Caton Street in the Del Ray section of the city for $300 a month, officials said.

According to police, Norton and Wanda Smith regularly babysit for each other. Last Friday Smith brought her daughter, Kathy Potts, to the Norton house as Smith and her husband took a Memorial Day vacation, police said.

When the couple returned on Sunday Norton and their child were gone, Uhrig said. Shortly afterwards they received a call from Smith's mother in Burlington, N.C., saying that Norton and Simeroth had just passed through, picking up Kathy's twin, Betty, and saying they were heading back to Northern Virginia, Uhrig said.

When they failed to return by Tuesday afternoon, Wanda Smith notified Alexandria police, who put out an all-states teletype message stating that Norton and Simeroth were wanted in connection with the children's abduction, according to Uhrig.

About 1 a.m. Wednesday a rented panel truck driven by Simeroth crashed into a ditch on a state highway about 65 miles from Montgomery, Ala., according to Tallapoosa County sheriff James Farrow. The couple was arrested when their names showed up on the police teletype, he said.

According to Dee Eadie, a social worker at Russell Hospital in Alexander City, the relationship between the two Potts children and the three Norton children "was like one big happy family. They all knew each other and were very friendly with each other. The kids were very much at ease with the adults," she said.