BOSTON (AP) _ The ninth victim of a serial killer who apparently preys on prostitutes and drug users in the seaport of New Bedford has been identified as a young mother, authorities said Thursday.

The victim, found Monday in the brush along Interstate 195 in Marion, was Sandra Botelho, 25, of New Bedford, a mother of two boys aged 4 and 6, officials said.

Her brother, Phillip Amaral, said the family struggled to explain to the boys what happened.

"We told them that their mother didn't run away," he said, crying. "We told them basically just somebody took their mother and he was bad to her and hurt her and now their mother died and went to heaven."

Botelho was reported missing by her family last August, and investigators said she probably was killed at that time. Her body was largely decomposed.

Dr. Stanley Schwartz, forensic dentist at Tufts University, used dental records to identify the remains Thursday at his Boston laboratory, said Jim Martin, a spokesman for the Bristol County district attorney's office.

Martin said both circumstances of Botelho's disappearance and the location of her body were similar to the other eight victims, all women 25 to 36 who lived in the New Bedford area and had ties to that city's Weld Square, a neighborhood known for prostitution and drug sales.

Martin said Botelho ''had a history of drug use,'' but he declined to comment on whether she was a prostitute.

All the victims found so far disappeared from New Bedford from April to September last year. The first body was discovered last July. All have been found along highways within 10 miles from the center of New Bedford.

State police using five search dogs continued combing roadsides for more bodies Thursday.

Bristol County District Attorney Ronald A. Pina has said he has several suspects, and a grand jury has been hearing evidence in the case, but no one has been indicted.