A Southeast Washington man suspected of carrying out a series of sexual assaults in the District, Virginia and Maryland was sentenced yesterday to a 37-year prison term for kidnapping and raping two teenage girls.

With his mother and other relatives looking on, Daniel Barnes, 28, apologized and asked for help at his sentencing in D.C. Superior Court.

"I'm sorry to the victims, for putting them through this, and to my family," Barnes said, looking to the back row of the courtroom, where his relatives were seated. Turning back to the judge, he said, "I just want to ask for your help."

Assistant U.S. Attorney Sharon Marcus-Kurn had asked for a 45-year prison sentence, and she maintained that it was a certainty that Barnes would commit more crimes upon his release.

Calling the crimes "shocking and horrifying," Judge Ann O'Regan Keary said that although Barnes may need therapy, he needs to be punished as well. For now any therapy will have to take place in prison, she said.

"The risk is too great that you will continue this dangerous pattern of behavior," she said.

By pleading guilty within a few months of his arrest last summer, Barnes had helped himself, Keary said. Prosecutors sought only half of the maximum 90 years allowed for the charges he had pleaded guilty to -- child sex abuse, armed sex abuse and kidnapping.

The first incident took place April 21, 2003, when Barnes brandished a knife and accosted two girls who were walking in the 3300 block of Minnesota Avenue SE, prosecutors said. One girl was able to flee, but a 14-year-old was pulled into a wooded area. Barnes later forced her into a car and drove her to another location, where he raped her, prosecutors said.

The second incident occurred Aug. 1, when Barnes abducted a 16-year-old girl who had just stepped off a bus and was walking along Elmira Street SW, prosecutors said. Barnes, wearing a ski mask and black gloves, grabbed her by the neck, dragged her behind a building, and raped her, they said.

A person who saw the abduction called police and pointed Barnes out to the responding officers. The victim had fled, but police located her and she identified Barnes as her attacker.

In both cases, DNA evidence recovered from the victims was a match with Barnes's DNA, prosecutors said. In December, he pleaded guilty.

When he showed up in court yesterday, Barnes seemed to have changed his mind. After conferring with him, his attorney, Gladys Joseph of the D.C. Public Defender Service, indicated that he wanted to back out of the agreement.

But after listening to the judge review the plea agreement and the evidence the government had said it would present, Barnes decided to go forward with sentencing.

Prosecutors and police say that Barnes has admitted to two specific attacks and that he claimed to have been responsible for others in the District, Maryland and Virginia. Police said he often wore a mask and sometimes used a knife. Police have asked anyone with information to call detectives at 202-576-6768.

At the sentencing, Daniel Barnes apologized and asked for help.