The reward for information about a 5-year-old New Jersey girl who vanished from a park last month has increased to $52,000, authorities said.

In a Facebook post Wednesday, the New Jersey State Police said it was contributing $10,000 to the reward as the duration of the search for missing Dulce Alavez nears a month. The little girl was playing in City Park in Bridgeton, a city in the southern part of the state, when she disappeared Sept. 16.

In addition to the contribution by the state police, the Philadelphia Lodge #5 Fraternal Order of Police gave $5,000 and two other donations for $1,000 each were added to the reward, according to the Bridgeton Police Department.

Five-year-old Dulce Alavez was last seen at a New Jersey park in Bridgeton on Sept. 16, 2019. Bridgeton Police Department

Police Chief Michael Gaimari Sr. said in a Facebook post Wednesday that investigators have "gathered a substantial amount of information" in the case, but they still need the public's help.

"We are in search of key information that we believe exists through the public that would greatly assist the investigation," he said.

Dulce's mother, Noema Alavez Perez, told police that she last saw her daughter playing on the swings with her 3-year-old brother at City Park. Perez said she was about 30 yards away in a car with an 8-year-old relative.

When her 3-year-old son returned to the car without Dulce, Perez said she began searching for her without success. Last week, authorities released the audio of the 911 call Perez made to a dispatcher. In it, the emotional mother told the operator that she couldn't find her daughter and that people at the park said somebody "probably took her."

Investigators have said that they are searching for a man, possibly Hispanic, who they say was seen leading Dulce from the park to a red van with a sliding door and tinted windows. Bridgeton police said in an update Oct. 4 that more than 500 vehicles had been investigated and over 200 locations searched.

The little girl was last seen wearing a yellow shirt with a koala bear on the front, black-and-white pants and white sandals. Dulce is described as Hispanic, with black hair and is roughly 3 feet, 5 inches tall.

The man police are searching for is described as having a thin build, light skin, no facial hair, and acne. He is said to be between 5 feet, 6 inches and 5 feet, 8 inches, and to have been wearing a black shirt, red pants and orange sneakers, which were possibly Nike brand, on the day Dulce vanished.