Neighbors of the Cremaciones del Pacifico crematorium said they had complained for weeks to local officials about the smell emanating from the abandoned building.
Some even told a witness that the piles of bodies were visible to the outside from a window in the dull one-story structure on the outskirts of the resort city of Acapulco, Mexico.
Yet authorities apparently did nothing until Thursday night, when officials discovered 61 bodies strewn about the crematorium in piles or near the facility's oven.
The bodies were mostly embalmed, some wearing suits as if ready for a funeral, and covered in white quick-lime powder.
'Some were wearing suits like they had just come from a funeral celebration.'
The state prosecutor confirmed Friday that the corpses included men, women, and at least one child. None of the bodies were found burned or dismembered.
Mexico's national security commissioner Monte Alejandro Rubido said that the building had been abandoned for at least seven months, and that the bodies had been decomposing for at least three months.
All of the corpses were fully or partially embalmed, and were being prepared for cremation, said Guerrero state prosecutor Miguel Angel Godinez.
"We are talking about a clear violation of sanitation laws in the state of Guerrero," he said.
The grisly discovery came as Mexico's government has sought to turn international attention away from the case of the 43 students forcibly disappeared by local police in the city of Iguala, Guerrero. As of Friday afternoon, there was no indication that the embalmed corpses belonged to the missing students.
"The bodies were piled on top of each other. Some were wearing suits like they had just come from a funeral celebration, and others were nude," Francisco Robles, a photographer who witnessed the recovery of the bodies inside the building, told VICE News.
"I think they had their funerals, and from there were sent off to their cremation, which never occurred," Robles said. "So my question is, Whose ashes were given to these families if they were never cremated? I mean the bodies are there, so whose ashes were they?"
According to Robles, neighbors said they had been reporting the bad smell to the local health secretary for at least three months. But officials told them they couldn't take further action because no one would answer the door.
Witnesses said there was no doubt as to what was inside the building.
"The first window on the left, if you look through it, you could clearly see the bodies," Robles said. "It was obvious. Even at night, using a flashlight, you could see the bodies there in plain sight. Now imagine during the day."
Neighbors finally flagged down a convoy of Mexico's gendarmerie military police force, they told Robles. Officials peered in and made the discovery, he said.
Authorities on Friday did not address claims that complaints about the building had been ignored. The state prosecutor said in a statement that authorities became aware of the bodies after an anonymous phone call.
The corpses were discovered throughout the building, with the majority piled near the metal crematorium oven.
"Once you enter, there are three offices, and one of them is used for performing the cremations. They found 55 bodies in that room," Robles said. "They found six more bodies in another room ... The smell was unbearable, it smelled like decay."
The head of the Guerrero funeral association is being questioned, the state prosecutor said at a Friday press conference. Authorities are also looking for the business's owner.
Officials said they would begin checking the crematorium records to make a list of everyone who was brought to the site since 2013.
The discovery occurred about 130 miles from the city where 43 teachers college students disappeared last September after an attack from Iguala police and members of the Guerreros Unidos drug gang.
"I hope none of the students are in that crematorium," Epifanio Alvarez, father of missing student Jorge Alvarez, told VICE News.
"You know, in Iguala there are too many bodies," Jorge's father said. "It's a grave. It's horrifying — and now this. And there are even more to come."
Follow Andrea Noel on Twitter @metabolizedjunk. VICE News reporter Melissa del Pozo contributed to this report.