New York (CNN) -- New York police arrested a Bronx man in connection with the 22-year-old killing of 4-year-old Anjelica Castillo, previously known as "Baby Hope," Police Commissioner Ray Kelly said Saturday.
The man, Conrado Juarez, 52, is the cousin of the girl, police said. He was arrested at a restaurant in Manhattan where he worked as a dishwasher, Kelly said.
Juarez admitted to the crime Saturday morning, Kelly said. Charges are still being developed, and it's not known yet when Juarez will be arraigned, Kelly said.
The arrest came as the result of an anonymous tipster who came forward, police said.
"Today, NYPD investigators have given young Anjelica her due justice," said Chief Phil Pulaski.
It was the first time police had identified the girl. For years she was known only as "Baby Hope," with no information about her or her family, and she was never reported missing.
Her body was found in a blue-and-white cooler in a wooded area near the Henry Hudson Parkway on July 23, 1991. She had been smothered and sexually molested, and her body was so badly decomposed that several sketches were made to suggest what she looked like.
Two years after she was found, the girl was laid to rest in a donated plot, buried in a white dress bought by a detective's wife, with a tombstone paid for by detectives. "Because we care" is the inscription at the bottom of the tombstone, Pulaski said.
The NYPD Cold Case Apprehension Squad never stopped looking for leads in the case, continuing to hand out fliers and canvass nearby neighborhoods every year on the anniversary of the July 23, 1991, discovery of the body.
The tip came after their latest canvass in July.
Changes in forensic science also helped push forward the investigation, Kelly said. The girl's body was exhumed in 2006, and a DNA profile was built in 2011. Earlier this month the office of the chief medical examiner made a DNA match between the girl and her mother.
From there, investigators constructed a family tree, and the trail led them to Juarez, Kelly said.
"It shows the phenomenal persistence" of the detectives who originally worked on the case and those now working with the cold case squad, Kelly said. "They were unrelenting."
Juarez, who was 30 at the time of the crime, said he went to an apartment in Queens shared by seven of his relatives and saw Anjelica in the hallway, Kelly said. Juarez told police he sexually assaulted her and then smothered her.
When the girl went motionless, Juarez told police, he summoned his sister from another room. It was the sister who told Juarez to get rid of the body and who provided the cooler, Kelly said.
The two hailed a cab to Manhattan, dropped the cooler off in a wooded area, and then went their separate ways, Kelly said.
The sister, Balvena Juarez Ramirez, is deceased, Kelly said.