Conrado Juarez, cousin and confessed killer of 4-year-old Anjelica Castillo, nicknamed Baby Hope, waits to be arraigned at Manhattan Criminal Court, Saturday, Oct. 12, 2013, in New York. During an interrogation early Saturday, Juarez admitted sexually assaulting and smothering her before disposing her body. Former NYPD detective Jerry Giorgio smiles alongside Commissioner Ray Kelly, right, after a news conference at One Police Plaza where it was announced that after an investigation that lasted more than two decades they had arrested the killer of a then unidentified child who was nicknamed Baby Hope, Saturday, Oct. 12, 2013, in New York. During an interrogation early Saturday, the 4-year-old Anjelica Castillo's cousin, Conrado Juarez, had admitted sexually assaulting and smothering her, Kelly said. Giorgio, who had the case from 1991 until his retirement over the summer, said he remained confident the case could be solved. NYPD Commissioner Ray Kelly speaks to the media during a news conference at One Police Plaza to announce that after an investigation that lasted more than two decades they had arrested the killer of a then unidentified child who was nicknamed Baby Hope, Saturday, Oct. 12, 2013, in New York. During an interrogation early Saturday, the 4-year-old Anjelica Castillo's cousin, Conrado Juarez, had admitted sexually assaulting and smothering her, Kelly said. (AP Photo/John Minchillo) Former NYPD detective Jerry Giorgio speaks to the media during a news conference at One Police Plaza after the police commissioner announced that after an investigation that lasted more than two decades they had arrested the killer of a then unidentified child who was nicknamed Baby Hope, Saturday, Oct. 12, 2013, in New York. NEW YORK (AP) - Detectives solved the decades-old mystery of "Baby Hope," a little girl whose body was discovered inside a picnic cooler beside a Manhattan highway in 1991, and arrested a relative of the child Saturday after he admitted he sexually assaulted and smothered her, police said. Conrado Juarez, 52, was arrested on a murder charge and was awaiting arraignment. Police Commissioner Raymond Kelly said Juarez claimed he killed the girl at his sister's apartment and that she helped him dispose of the body. The sister has since died, police said. They were cousins of the little girl's father. The girl's name, age and circumstances of her death were unknown for more than two decades. But earlier this week, police announced that a new tip and a DNA test had allowed them to finally identify the baby's mother, a dramatic turnaround in one of the city's more notorious cold cases. On Saturday, they also revealed the girl's name: Anjelica Castillo, age 4. The child's naked, malnourished corpse was discovered on July 23, 1991, beside the Henry Hudson Parkway by construction workers who smelled something rotten. Detectives thought she might have been suffocated but had few other clues as to what happened. The case became an obsession for some investigators who nicknamed the girl "Baby Hope." Hundreds of people attended a funeral for the unknown girl in 1993. Her body was exhumed for DNA testing in 2007, and then again in 2011. In July, detectives tried another round of publicity on the 22nd anniversary of the discovery. They canvassed the neighborhood where her body was found, hung fliers, circulated sketches of the girl and a photograph of the cooler and announced a $12,000 reward for information leading to an arrest. Former detective Jerry Giorgio, who had the case from 1991 until his retirement over the summer, said he remained confident the case could be solved. Assistant Chief Joseph Reznick, who also worked the case, said they never gave up. "I think reflecting back on what we named this little girl, Baby Hope, I think it's the most accurate name we could have come up with," Reznick said. Giorgio left the NYPD and went to the Manhattan district attorney's cold case squad, from which he retired this year. "I missed the tipster call by a couple of weeks, damn it," he said. The tipster, who saw the recent news stories on the case, led police to Anjelica's sister, who told detectives she thought her sister had been killed. Police matched DNA from Anjelica to their mother. The mother, who was not identified, didn't have custody of Anjelica at the time of the girl's death - she had been living with relatives on the father's side, including Balvina Juarez-Ramirez, police said. Juarez-Ramirez is the sister of Juarez. Police closed in on the suspect and waited for him Friday outside a Manhattan restaurant where he worked as a dishwasher. He told them he noticed Anjelica while visiting the family apartment and killed her, police said. "When she went motionless, he summoned his sister from another room," Kelly said. Then, the sister got the blue cooler - which still contained full cans of Coke. They took a livery cab from Queens to Manhattan where they dumped the cooler, then separated. Her parents never reported her missing, though they had contact with the suspect. Juarez had never been considered a suspect before. Police refused to say whether he had previous arrests or had been accused in other sexual assaults. Kelly called the arrest a superb case of detective work, and said he was proud of his officers. "For me, it makes you proud to be a member of this organization - they were unrelenting," he said. The detectives assigned to the case were instrumental in organizing a burial in a Bronx cemetery for the girl in 1993. Hundreds attended the funeral; Reznick gave the eulogy. The detectives paid for the girl's headstone that reads: "Because we care." On the tomb sit two little angels. Associated Press writer Jake Pearson contributed to this report.