Maryland State Police and FBI agents continued to search yesterday for a Florida prison escapee who ran from an Eastern Airlines plane at Baltimore-Washington International Airport Friday with a 6-month-old boy believed to be his son, officials said.

FBI agents yesterday identified the suspect as William Thomas Forrer, who has escaped twice from authorities: in 1983 from federal prison in Florida, where he was serving time for interstate auto theft, and in August 1984 from a jail in Sebring, Fla., where he was taken after the first escape.

Forrer is also wanted for interstate auto theft and assaulting a federal officer, an FBI spokesman said.

Identifying himself as Walter Stanton Leber, 30, of Fredericksburg, Va., and carrying the baby boy, Forrer had boarded the Fort Lauderdale-bound plane at about 4 p.m. Friday, police said.

He handed the baby to a flight attendant while he went into a restroom, then returned to his seat, retrieved the baby and ran off the plane, police said.

After leaving the plane, the suspect jumped into a parked airport van and drove off, leading police on a chase down Rte. 46, officials said. Half a mile from the airport he pulled off the road and escaped on foot, they said.

Maryland State Police spokesman Chuck Jackson said the baby was rescued and turned over to the Anne Arundel County protective services department.

Jackson said state police investigators do not know why Forrer was in the Baltimore-Washington area or why he boarded the aircraft. He said it also was not clear at what point police recovered the infant. An FBI official said it was a strong possibility that the infant was Forrer's son, whom he said the fugitive had been seeking for some time.

Police said they found three small bags of a substance believed to be marijuana in the plane's restroom and recovered a cardboard box with $35,000 in cash from the plane.