Eleanor Carlson warned her neighbors that if anything bad ever happened to her, they should tell police to go looking for her son. The 72-year-old San Rafael woman had obtained a restraining order against him and was so afraid she intended to reinforce her doors.

About 4 a.m. Monday, one of her neighbors, John Diego, heard an "awful, awful scream" coming from the widow's home on the 200 block of C Street, a few blocks south of downtown. When police arrived, they found her on the floor. Her throat had been slashed, authorities said.

Police would not name the victim, but neighbors identified her as Carlson. Within hours, police around the Bay Area were looking for her son, Richard Leroy Carlson, 30, whom San Rafael investigators called "a person of interest." They warned that he was believed to be armed with a knife.

Eleanor Carlson long had problems with her son, neighbors said.

In January, police responded to the home to investigate a report that Richard Carlson had attacked his mother during a "violent confrontation," said Margo Rohrbacher, a San Rafael police spokeswoman.

Eleanor Carlson obtained a temporary restraining order against her son that was served Wednesday, authorities said. Richard Carlson had not been charged in the January case, but Marin County prosecutors were reviewing it, police said.

Richard Carlson is a "logical person" for police to talk to about his mother's death, given the earlier incident, Rohrbacher said.

His last known address was in Oakland, Rohrbacher said, and police in the Bay Area were told he could be headed to a West Oakland soup kitchen or to Laney College in Oakland, where he is a student.

About two weeks ago, Eleanor Carlson said her son had tried to choke her and had demanded money from her, said Diego, who knew her for 40 years and whose home is behind Carlson's. She told Diego to call 911 if he ever heard her scream, and to tell police that her son might be responsible, Diego said.

She had been planning to have her doors reinforced and have a new security system installed, Diego said.

Neighbors said they often saw Eleanor Carlson standing in front of her home in a bathrobe and curlers, looking dejected. She lived alone after her husband, Richard Carlson, a Golden Gate Bridge toll collector, died in 1989.

"She was not happy," Diego said.

While walking his black Labrador retriever through the leafy neighborhood, Steven Schoonover, who lives around the corner from the victim, said, "This is surprising and sad. She didn't impress upon me as a person who had any enemies."