After four days on the run, a Kentucky woman and her boyfriend are in police custody in Illinois, accused of kidnapping her 9-month-old son from a social worker, later found dead, who had taken the child to visit the mother.

The infant was examined by a doctor and found in good condition, FBI agent John Stafford said at a news conference Thursday at the Alton Law Enforcement Center, where the couple were being held.

FBI agents arrested Renee Terrell and her boyfriend, Christopher Wayne Luttrell, about 8:30 p.m. Thursday in a rural area near Godfrey, about 35 miles north of St. Louis, Stafford said. The baby, Saige, was with them.

Stafford could not say when Terrell and Luttrell would appear in court for an extradition hearing for their return to Kentucky.

Sgt. John Nevels of the Henderson, Ky., police department said the couple were caught hiding in a camper where they had sought shelter after their car apparently broke down and got stuck in mud.

"They were getting pretty desperate and had run out of money and food," Nevels said. "They started reaching out to people to try and help them."

Nevels said he didn't know why Terrell, 33, and Luttrell, 23, had fled to Illinois, but authorities had been searching the area for them after contacting the couple's friends and family.

Earlier Thursday, the FBI had issued warrants for the couple for unlawful flight to avoid prosecution on state kidnapping charges, according to Tracy Reinhold, an FBI agent in Kentucky.

The baby had been removed from Terrell's custody when he was 13 days old because of neglect, according to police. On Monday, social worker Boni Frederick, 67, took the boy to his mother's home in Henderson for a visit.

Frederick was found beaten to death at the house later that day, and the baby, his mother and Frederick's station wagon were gone, authorities said.

Frederick's purse was found near Mount Vernon, Ill., about 100 miles southeast of Godfrey, said Henderson police Detective Ron Adams.

A neighbor, Jean Davis, told The Courier-Journal that Terrell learned last week that the boy was to be put up for adoption. Terrell told friends on Saturday she planned to take the boy and run away to New Mexico, Davis said.

"She loved her baby," Davis told the newspaper in a story published Wednesday. "She talked about how she was going to get her baby and everything back. She was buying clothes. She had a baby bed and a high chair and everything. ... I guess it made her snap."