Police in Mexico City have scoured a hilly urban park for feral dogs and tested dozens of captured animals in a hunt for those responsible for four fatal maulings.
Authorities have captured 25 dogs near the scene of the attacks in the capital's poor Iztapalapa district.
The bodies of two teenagers, an adult and a one-year-old boy were found at separate locations and dates in Cerro de la Estrella park.
However, rather than calm residents, photos of the dogs brought a wave of sympathy for the animals and debate about government handling of the stray dog problem.
Activists started an online campaign protesting the dogs' innocence and calling for authorities not to put them down.
Tens of thousands of dogs are put down each year in Mexico if they are captured by animal control officers and not claimed within 72 hours.
Many people re-posted the images of the dogs staring sadly from behind bars at an animal shelter.
The hashtag for the campaign became the top trending topic on Twitter in Mexico, with some users furiously accusing the authorities of cruelty to animals and others sarcastically calling the dogs "political prisoners" and mocking the fuss over the fate of the animals.
Officials said they were testing the captured dogs' fur for blood, and examining their stomach contents to determine if they were the killers of the four people whose bodies were found covered in dog bites in two separate incidents in recent days.
Neighbours of the Cerro de la Estrella park found the bodies of a 26-year-old woman and a one-year-old child in the area on 29 December, authorities said.
The woman, Shunashi Mendoza, was missing her left arm, and prosecutors said that both she and the boy had bled to death.
On Saturday visitors to the park found the bodies of Alejandra Ruiz, 15, and her boyfriend Samuel Martinez, 16, who were found dead from blood loss.
The girl called her sister Diana Ruiz at around 7pm pleading for help, the sister said.
Mexico City prosecutors said that due to the nature of the wounds they believed at least ten dogs were involved in each attack.
Dozens of officers returned to the park yesterday to capture more of the feral dogs, which live in caves and hollows in the area.
The furore has forced a public response from Mexico City Mayor Miguel Angel Mancera, who called for animal-rights groups to help study the guilt or innocence of the 25 dogs, and the broader effort to reduce the number of street dogs in Mexico City.
"We're not taking any decision. The dogs are in a shelter and we have to check on their health," he told reporters after a midday press conference.
He also said the government would launch a new program to spay and neuter dogs, sending 25 mobile surgical units to neighbourhoods where residents would be encouraged to take advantage of free sterilisation for their pets.
