Dulce's face is all over Amber Alert posters, but still, she's nowhere to be found. The FBI has also recently placed Dulce on its most-wanted missing persons list.
WATCH: The family of Dulce Maria Alavez issued a plea
Officers said a man led Dulce away to a red van while she played with her 3-year-old brother back on September 16 at the Bridgeton City Park.
Investigators said it happened while her mother was in the car with an 8-year-old relative.
WATCH: Last images of Dulce Maria Alavez before she went missing
Dulce's mother told police her son soon ran back to the car crying and pointed to the area where he last saw his sister. They looked but could not locate her.
Kimberlee Sue Moran, a teaching professor and director of forensics at Rutgers University-Camden, is not involved in the investigation but is familiar with how large-scale searches work.
"Investigators cast a wide net. Connecting the dots to what is a dead-end and what is not," she said. "In forensic science, it is all about inclusion or exclusion so what sort of suspects or scenarios can we exclude."
TIMELINE: The search for missing 5-year-old girl Dulce Maria Alavez
The Cumberland County prosecutor said earlier this week that many agencies, including the FBI, are tirelessly working leads in hopes of finding Dulce.
Officials were able to reach Dulce's father Tuesday by telephone in Mexico, where he lives.
Today, they aren't giving any details on the progress made from that conversation.
EXPLAINED:What are the criteria for issuing an Amber Alert?
The official reward total for information that leads to solving the case is $35,000.
Anyone with information is asked to call the FBI.