James Dixon, 25, was charged on March 3, 2015 with killing Islan Nettles. He is pictured heading to be arraigned on the indictment in Manhattan Criminal Court. On April 4, he pleaded guilty to the crime. View Full Caption DNAinfo/Ben Fractenberg

MANHATTAN SUPREME COURT — A 25-year-old man charged with beating a transgender woman to death in Harlem nearly three years ago has pleaded guilty to the attack, prosecutors said Monday.

James Dixon admitted to punching 21-year-old Islan Nettles to the ground when he and a group of friends passed the woman along Eighth Avenue, between W. 147 and W. 148 streets, shortly after midnight on Aug. 17, 2013.

Dixon's blow sent Nettles crashing to the pavement, knocking her unconscious, but Dixon continued to punch her as she lay on the street, prosecutors said.

Nettles was taken to the hospital, and was declared brain dead as a result of her injuries and taken off life support three days later, prosecutors said.

A different man, 20-year-old Paris Wilson, who was with Dixon at the time of the assault, was initially arrested shortly after the attack. But charges were dropped against Wilson, a Harlem man, several months later.

It wasn’t until last March, nearly two years after the fatal beating, that Dixon was arrested and charged with manslaughter.

Dixon — who told DNAinfo New York from jail that prosecutors had the wrong man — admitted in a taped interrogation, played in court Friday, that he felt his "manhood" was threatened after he tried to hit on Nettles, not realizing she was transgender, the Daily News reported.

Dixon is expected to be sentenced on April 19. He could face up to 25 years in prison.