FARMINGDALE, N.Y. (AP) -- A man with a history of psychiatric problems decapitated his mother, dragged her lifeless body into the street in front of their home and then killed himself by walking into the path of a nearby oncoming train, police said Wednesday. Neighbors initially took the woman's killing as a macabre Halloween prank. Patricia Ward, a 66-year-old professor, was killed Tuesday night in her Farmingdale apartment just steps from a Long Island Rail Road station, Nassau County Police Detective Lieutenant John Azzata said. Her 35-year-old son, Derek Ward, committed suicide several minutes later by walking in front of a commuter train approaching the station, Azzata said. Patricia Ward was found dead in the street at around 8 p.m. Tuesday. Her torso was found by a curb and her head was several paces away, police said. A knife was recovered in the apartment, police said. Dale Silverman, a medical editor who lives in the same Long Island community, was driving away from the train station shortly before police arrived. "I saw what I thought was a head in the street. I saw long, black, straight hair and the head face down," she said Wednesday. "And I did a double-take. And I opened the window and said, 'No, that can't be what that is.'" "I saw the body, completely straight legs together, hands at its side," said Silverman, pointing to still-bloodstained areas of the street several yards apart. "It looked fake," she said. "I thought it was a stupid Halloween prank." Derek Ward was arrested years ago for gun possession and criminal mischief and had a psychiatric history going back about 10 years, authorities said. The mother and son had lived in the apartment for about three months, and police had no record of any domestic violence complaints, Azzata said. Neighbors didn't report any sounds of arguing between the two in the hours preceding the killing, he said. Patricia Ward, who taught language arts in a program that prepares high school students for college, "was a member of the campus for 28 years," Farmingdale State College said in a statement. "She was well-known, well-liked and well-respected. The campus is a very sad place today." Karen Coutrier, the interim director of the program, told The Associated Press her colleague "was a very quiet and soft-spoken person." She said Ward never mentioned her son's psychological issues. "She was a very private person, a very private person," Coutrier said. The body was found near a home decorated with Halloween pumpkins, fake cobwebs and a mock graveyard. "At first, everyone thought it was like a Halloween prank," said neighbor Barbara Smalls, recalling Wednesday morning how she had seen the sheet-covered body. She also "thought maybe it was a mob hit or something." "This doesn't happen here," said Smalls. "This is a very nice, nice neighborhood. People are very friendly."