KEYMAR, MD. -- Federal officials returned to Carroll County yesterday to look into the cause of a small-plane crash that killed one man and left another in critical condition.

The Federal Aviation Administration began the investigation shortly after the 1:40 p.m. crash Friday in Keymar.

Trooper Greg Shipley said a Piper single-engine aircraft piloted by Patrick Williams, 46, crashed after takeoff from the Keymar airport.

Shipley said the pilot was killed immediately. His son, Patrick Williams Jr., 20, remained in critical condition yesterday at the University of Maryland Shock-Trauma Center in Baltimore.

The men lived in the Detour area of Frederick County.

Officials said the pilot was a 15- to 20-year flying veteran and a member of the Civil Air Patrol.

The Piper aircraft was a new plane that Williams had bought six weeks ago, a neighbor told officials.

Witnesses told investigators that shortly after taking off from the Keymar Airpark, the plane began banking left about 50 feet off the ground. But the plane lost altitude and crashed into a rye field about a quarter mile from the airstrip.

The Civil Air Patrol secured the area after the crash for federal investigators, who resumed their search of the plane and area Saturday.

Joan Crotts, a neighbor and friend of the pilot, said that about the time of the crash, Williams' wife Sandra was looking for her husband and son because they were late for Christmas dinner.

Crotts said Sandra Williams thought they had taken the plane for a spin and went to the airport to look for them, only to discover police cars and rescue workers.

"She knew he was dead then and there," Crotts said.