Prince George's County and federal law enforcement officials said yesterday that they had been unable to locate or identify a woman who may have information about Jeremiah Thate, the 3 1/2-week-old infant who was abducted Thursday from the Prince George's Hospital Center.

Also yesterday, police announced a $15,700 reward for information leading to the arrest and indictment of anyone responsible for taking the baby from the pediatric ward of the hospital in Cheverly. Money for the reward was raised from civic groups, private citizens and the Thate family, police said.

Police showed the baby's parents a composite drawing of the woman early yesterday, but the couple did not recognize her. "They said that they had not seen the woman before," said police spokesman Bruce Gentile.

The FBI developed the sketch of the woman after a nurse said that she had seen a woman hanging around the baby's room on the sixth floor of the hospital. The woman is described as 25 to 30 years old, 5-foot-5 and 175 pounds, with dark blonde hair worn in a ponytail.

Both the police and the FBI emphasized that the woman is wanted for questioning but is not a suspect. "We want very much to talk with her," said Greg Jones, a spokesman for the FBI field office in Baltimore.

Federal officials became involved in the case on Monday, an FBI spokeswoman said, because 24 hours after a person has been missing "it is assumed that the victim could have been taken across state lines."

Police and the parents, Robert and Theresa Thate, who live in Hyattsville, have not received calls or notes requesting a ransom for the infant. "Perhaps whoever has the child intends to keep it," Gentile said.

Police are asking anyone with information on the case to call 735-1111. All calls will be treated confidentially.