Kentucky police think they have their first break in the hunt for two suspects wanted in the vicious murder of an elderly social worker and the kidnapping of a disabled 9-month-old boy.

A videotape taken late Monday night at a gas station in Smithboro, Ill., about 50 miles northeast of St. Louis, appears to show one of the suspects, Christopher Wayne Luttrell, 23, getting out of the passenger's side of the victim's car to pump gas, Henderson police said. A trace of the credit card used by the man showed that it, too, belonged to the victim.

The other suspect, Renee Terrell, 33, and the boy's mother, was believed to be driving the car, police said. It was not known in what direction the car drove off.

The couple are wanted for allegedly beating and cutting to death Boni Frederick, 67, a social worker who had taken the 10-month-old boy, Saige, to Terrell's house for a visit, police said. The boy was described as being developmentally disabled.

Police found Frederick's body at the house on Monday after she failed to return to work. Her car also was missing

"It was blunt force trauma and sharp instrument lacerations," Sgt. John Nevels of the Henderson Police Department said Tuesday. "There was definitely a struggle."

Terrell has a history of abuse charges against children, including charges of assault and endangering the welfare of a minor, police said. The child had been taken from his mother when he was 13-days-old because of neglect.

Luttrell has separate burglary charges in Jefferson County and has a warrant for parole violation, police said.

Investigators have contacted family and friends, who have been "helpful on giving some locations to concentrate on" in their search.

The FBI also is investigating the case.

A neighbor, Jean Davis, told The Courier-Journal newspaper that Terrell learned last Wednesday that Saige would 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. "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."

Neighbor Mindy Gray, 22, described Terrell as "goofy, like a little kid."

"But every time I talked to her, she was sweet as can be," she said.

Gov. Ernie Fletcher asked flags to be flown at half-staff on state buildings in memory of Frederick, who worked for the state Cabinet for Health and Family Services. The last time a social worker was killed on the job in Kentucky was in 1987.

Advocates said the slaying emphasizes the danger of social work.

"It's like a state trooper stopping somebody for speeding," said Kathleen Hoffman, deputy director of the Association of Social Work Boards. "Ninety-nine percent of the time it's fine. But there's always that chance that somebody has a gun."

Terrell has family in Louisville; Evansville and Fort Wayne, Ind., and New York, police said.

Frederick's car was described as a 2000 white Daewoo Nubia station wagon with Kentucky license plate 675-DRV, police said.

Renee Terrell was described as white, brown hair, brown eyes with glasses, 5-foot-5 and 240 pounds. Luttrell was described as white, blue eyes, 6-2 and 150 pounds with tattoos on his arms.

Saige Terrell is white, brown eyes, brown hair, 27 inches tall and 19 pounds. Police said the boy has a scratch on the right side of his face and a rug burn on the back of his neck.

Information about the missing boy can be reported to police at (270) 827-8700.