A Brooklyn high school teacher accused of having sex with a 16-year-old student surrendered to the police on Thursday, two days after Mayor Michael R. Bloomberg called on state lawmakers to pass legislation that would give New York City greater power to fire teachers accused of sexual misconduct.

The teacher, Erin Sayar, an English teacher at James Madison High School, in the Midwood neighborhood, is accused of having sex with the boy at least eight times in the past school year, according to a report issued by Richard J. Condon, the special commissioner for investigation for the city’s schools. The Daily News reported on the case on Thursday.

Sandy Silverstein, a spokesman for the Brooklyn district attorney’s office, said he expected charges to include third-degree rape and third-degree criminal sexual act, both felonies. Ms. Sayar will most likely be arraigned on Friday, he said.

An effort to reach Ms. Sayar, 36, for comment was unsuccessful.

On Tuesday, Mr. Bloomberg endorsed a bill that would give school superintendents in the state — including Dennis M. Walcott, the city’s schools chancellor — the last word on whether teachers facing sexual-misconduct accusations are fired.

The current system leaves the decision up to an arbitrator chosen by the district and the teachers’ union.

The issue of inappropriate behavior by teachers in New York City schools has attracted much attention in recent months, following the arrests of a number of school employees accused of sexual offenses involving students.

In an interview on the John Gambling radio show on Thursday morning, Mr. Walcott said he would “never accept” teachers having any sexual contact with students, regardless of whether or not it was illegal.

The student in the James Madison case and his mother began legal action in State Supreme Court in Brooklyn against the city’s Education Department on Wednesday, seeking compensation for psychological harm and other damages. The court filing also claims that the teacher gave the student marijuana she had kept in a file cabinet.

Marge Feinberg, an Education Department spokeswoman, said Ms. Sayar was reassigned in January to an administrative office away from classrooms. “We’re in the process of seeking her termination,” she said.

The city’s investigation into Ms. Sayar began in January after a girl who had been romantically involved with the student at the center of the case filed a complaint with the school about comments Ms. Sayar had made to him on Facebook, officials said.

The girl told investigators that she had exchanged Facebook passwords with the boy and had read a series of conversations between him and Ms. Sayar on the site.

In one message to the teacher, he wrote, “i love you so much,” according to the report. The student told investigators that he had received permission from his gym teacher to miss class and meet with Ms. Sayar for tutoring twice a week. The report indicated that Ms. Sayar was married and had a young child.

Ms. Sayar and the student made a total of 19 calls to each other and exchanged 3,856 text messages over about a month, according to the report.

One night in December, the student sent Ms. Sayar a text message asking her to come to his apartment. She arrived after midnight, the report said, and the student came down and got in her S.U.V., where they had sex.

James Madison High School’s principal, Joseph A. Gogliormella, declined to comment on the case.