Tonya Fea, 47, of Jefferson Township "reportedly confessed," The Last Resort Animal Rescue announced Tuesday.
"But, much to our horror, our worst fears were confirmed: The official [necropsy] report confirms that drowning was the cause of death," officials with the non-profit organization wrote.
The dog "was intentionally drowned," they said.
The Last Resort, which named the dog Jenny, had posted a reward that quickly ballooned to $12,000, thanks to contributions.
It also launched the hashtag #JusticeForJenny.
"We have asked the investigators to put us in contact with the two people responsible for seeing our post and calling in the tips that led them to making this arrest," the Last Resort's organizers wrote. "Once she's convicted we can give them their rightful reward."
It began when a Last Resort rescue member spotted the crate at the edge of in Greenwood Pond on Bonter Road on the Oak Ridge side of town on April 30.
A man had pulled the cage from the water and left it there, they said.
"The puppy was dead and ice cold and soaking wet inside the crate, lakebed vegetation hanging on the crate," the organization's Nancy Warner wrote.
Also in the cage with Jenny was a wee-wee pad and a lead-crystal ice bucket that authorities believe was used to weigh it down.
The pads had some blood on them and were stuck to Jenny's head.
Jenny was taken to the New Jersey Department of Agriculture’s Animal Health Diagnostic Laboratory, where a necropsy was conducted.
Meanwhile, township police detectives discovered that Fea had made an appointment at the West Milford Animal Hospital for a Golden Retriever puppy the same day that Jenny's body was found but didn't show up or cancel, according to court records.
Things fell into place rather quickly after that.
Fea is charged with two counts of animal cruelty and one of trespassing, authorities said.
Fea was released pending a May 22 first appearance in Central Judicial Processing Court in Paterson, Passaic County Prosecutor Camelia M. Valdes and West Milford Police Chief Timothy Storbeck said in a joint announcement.
PHOTOS: Courtesy GREENWOOD LAKE ANIMAL HOSPITAL
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PREVIOUS STORY: The reward on Friday rose to $12,000 for anyone providing information that helps catch the killer of a 10-week-old puppy who'd been submerged in a weighted cage in a West Milford pond.
At the same time, township police announced that the person who apparently pulled the cage from Jennings Pond in the Oak Ridge section of town had come forward.
The carcass of the female Golden Retriever -- dubbed "Jenny" -- was found Tuesday in the cage with an ice bucket that helped weigh it down, authorities said.
They didn't specify what brand of bucket, although an online search produces similar pieces made in Eastern Europe that sell for $18 to $29.
With no suspects identified by authorities, the Last Resort Rescue offered the reward. Contributors have helped increase it the past several days.
The non-profit animal mission also launched the hashtag #JusticeForJenny.
"One of our rescue officers at The Last Resort Rescue noticed a crate at the edge of the pond on Bonter Road on the oak ridge side of town [Tuesday] with a puppy in it," wrote Nancy Warner.
"The puppy was dead and ice cold and soaking wet inside the crate, lakebed vegetation hanging on the crate, with a lead crystal vase (notice garage sale price tag) and wee-wee pads stuck to the side of her head with a small amount of blood on them," Warner said.
On Friday, West Milford police said that the man who spotted the cage, pulled it out of the water with the puppy inside and left it at the water's edge had come forward.
A friend of his described the man as "a foster/rescuer who is an avid animal advocate and lover."
Police said the investigation is "progressing quickly and we are awaiting preliminary necropsy results" by the New Jersey State Agricultural State Lab to determine when and how the puppy was killed.
They asked that anyone who saw or knows something about the incident to contact the Passaic County prosecutor’s tips line at 1-877-370-PCPO or tips@passaiccountynj.org or West Milford Detective Eric Darnsteadt at (973) 728-2801.
The lead-crystal ice bucket (above) weighed down the cage. Authorities hope it provides the clue that helps catch Jenny's killer.
PHOTOS: Courtesy GREENWOOD LAKE ANIMAL HOSPITAL
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