When police asked Carrasquillo why he had attacked the girl, he said: "It was drugs. My mind was telling me to do it. The rage I had about [the female friend] and the black guy - black people in general.
"I've been locked up and in placement with black people my whole life. They treated me bad and they think they are the supreme race. I went berserk."
His victim, who was a fifth-grader at Russell H. Conwell Middle School, "happened to be in the wrong place at the wrong time," prosecutor Thurston said.
Carrasquillo spotted her at 8:20 a.m. as she walked her younger sister to a Kensington day-care center.
After dropping her sister off and heading for school, the girl was followed by Carrasquillo, who eventually approached and made small talk before pulling her into an alley on Westmoreland Street near Emerald.
"He sexually assaulted her in every way imaginable," Thurston said.
After the girl began to bleed heavily, Carrasquillo said he told her: "That's what happens. It's OK."
The girl's injuries required surgery and a three-day hospital stay.
The next day, after police labeled Carrasquillo a person of interest in the attack, he was beaten and held for police by citizens who spotted him at Front and Clearfield streets.
His DNA matched DNA collected from the victim's underwear, Thurston said.
Carrasquillo, with short-cropped hair and long chin whiskers, remained handcuffed in court. When the judge asked how he was feeling, he replied that he felt nervous.
After affirming his decision to forgo a trial, he pleaded guilty to a battery of charges including aggravated assault, ethnic intimidation and rape of a child with serious bodily injury, which carries a maximum sentence of life in prison.
Carrasquillo also pleaded guilty to indecent assault and unlawful contact with a minor, for grabbing a 16-year-old girl's breast and following her to school an hour before he committed the rape.
Djerassi said that he would be "vigilant" about keeping Carrasquillo safe in jail, although he did not elaborate.
In April, after Carrasquillo reportedly attacked guards at Curran-Fromhold Correctional Facility, he was beaten by them and taken to the hospital in critical condition.