A 24-year-old District man who learned belatedly that the prostitute he had propositioned was a man admitted yesterday to killing the sex worker soon after their encounter.

Antoine Jacobs, who was to go on trial yesterday in D.C. Superior Court, instead pleaded guilty to second-degree murder, avoiding the possibility of a life sentence if convicted.

Appearing before Judge John H. Bayly Jr., Jacobs admitted that he had hunted down and then shot and killed Elviz Augusto Perez Morales early on the morning of Aug. 16, 2003.

A drag performer whose stage name was Bella Evangelista, Morales was one of two transgender people killed in the District that month under similar circumstances.

The slayings of Aaryn Marshall and then Morales less than a week later aroused fears that transgender people were being targeted for violence.

Like Morales, Marshall was working as a prostitute and was killed when a patron discovered that Marshall was male. But the motive in that slaying had remained unclear until the sentencing of Marshall's killer, Derrick A. Lewis, who explained in November what had prompted his attack.

In the slaying of Morales, however, the role of sexual orientation was apparent early on, and prosecutors charged that it was an aggravating factor against Jacobs. If a jury had concluded that Morales was killed because of sexual orientation, Jacobs could have been sentenced to life without parole.

Instead he faces a likely sentence of 12 to 24 years -- the recommended range for a second-degree murder conviction, with a maximum of 40 years.

Standing before the judge, Jacobs listened as the prosecutor, Assistant U.S. Attorney Michelle D. Jackson, and the defense attorney, Frances D'Antuono, outlined what happened in the first hours of Aug. 16, 2003.

Jacobs had just turned 22 and was celebrating with friends in his neighborhood in the area of Allison Street NW, D'Antuono said. For hours, his friends had been plying him with Remy Martin, and by the time he encountered Morales, Jacobs was "extremely intoxicated," the defense attorney said.

Seeing Morales at Allison and 13th Streets NW, Jacobs approached, Jackson said, and a deal for oral sex apparently was struck. When Jacobs returned to his friends, one of them, upon hearing of the sex for sale, went to look for Morales. But the man soon returned and said Morales "did not look right," Jackson said.

Jacobs, apparently agitated by talk that the prostitute was not a woman, obtained a gun and went on his bicycle to look for Morales, Jackson said. Finding the sex worker at Allison Street and Arkansas Avenue NW, Jacobs confronted Morales.

Morales, fearing a robbery, offered to return the $20 Jacobs had paid. But Jacobs made it clear he was not after the money. He wanted to know whether Morales was a man or a woman.

Moments later, he opened fire, striking Morales three times.

Police officers on patrol nearby heard the gunfire and rushed to the scene.

Spotting Jacobs fleeing on the bicycle, they gave chase, pursuing him first from the car and then on foot across a baseball field, where Jacobs tried to ditch the gun but didn't outrun the police.