A District elementary school teacher admitted Friday to sending a lewd Facebook message to a 12-year-old student, an act that D.C. Public Schools officials called “abhorrent, inexcusable behavior.”

Jurelle V. Turner, 46, pleaded guilty in D.C. Superior Court to “certain obscene activities and conduct,” a misdemeanor. School system officials said they have begun efforts to fire him.

“Teachers are expected to act as professionals and behave accordingly,” spokeswoman Melissa Salmanowitz wrote in an e-mail. “What’s been alleged is illegal and a gross abuse of power. It is abhorrent, inexcusable behavior.”

Turner was placed on paid leave from Brookland Education Campus at Bunker Hill after police launched an investigation in April, and officials alerted the school community of his leave at that time. They did not explain why, Salmanowitz said, because of a policy against commenting on ongoing personnel matters.

They also were not privy to details of the police investigation into the allegations against Turner, she said.

Brookland officials referred questions to DCPS on Friday. Salmanowitz said the school sent parents a message with full details Friday after Turner’s guilty plea. But some parents said they were upset that they weren’t told when police first became involved.

“I think we should have been told as soon as any hint of wrongdoing was found,” said Aurelia Williams, president of the school’s PTA. “Teachers are entrusted with the well-being of our children all day, and I feel we should be notified” when there is suspicion that a law has been broken, she said.

Turner had worked for the school system since 1994. He most recently taught first grade at Brookland, a school for pre-K through eighth grade in Northeast Washington.

The victim was a Brookland student and the older sister of one of Turner’s first-graders, according to court documents. Turner began conversing with the girl via Facebook in August 2011, prosecutors said, using the site to send her a video in March.

The video depicted a girl with her hands inside her pants and was accompanied by a comment, according to court documents, in which Turner asked, “is this girl playing with her self or masturbating at school?”

Turner challenged part of that version of events in court Friday, saying that the girl posted the video on his page first and that he had only commented on it. But he said he knew what he had done was wrong.

“I’m not making excuses. I said what I said, I did what I did,” he said. “My apologies go out to the student and her family. . . . I’m a good person, and I love children, and I just made a poor decision.”

Authorities said police learned of the video after someone discovered the Facebook correspondence between Turner and the victim. DCPS officials said they were not aware of other complaints of sexually inappropriate behavior by Turner.

Judge Judith E. Retchin is scheduled to sentence Turner on Oct. 9. He could face a maximum penalty of 180 days in jail and a $1,000 fine, and may be required to register as a sex offender.