The Animal Concerns Research and Education Society (Acres) made a police report yesterday about a possible case of animal abuse.
It had found a dead python near an emergency exit in an upper parking deck of Bukit Timah Plaza last Wednesday evening with its head and body crushed, and a cigarette butt in its mouth.
This follows a spate of cat deaths in Yishun in the last two months, with the most recent case occurring last Friday morning.
Ms Anbarasi Boopal, deputy chief executive of Acres, said: "There was no CCTV in the area, so we're trying to get more information on the incident.
She said that the mall's security guards had alerted Acres to the snake, and a team from the society had arrived within 10 minutes.
"We have come across other incidents where snakes are killed because people fear them. They don't know that snakes can be left alone," she said.
"But this incident looks different," she added.
"It looks like the snake was hurt and stepped on as there's trauma to the head.
"Its skin at the rear portion was stuck to the floor and there was a cigarette placed in its mouth.
"It couldn't have been run over by a vehicle because it was on a walkway and not on the driveway."
The snake,which was up to a metre long, was a reticulated python, a species that is commonly found in Singapore. Its carcass is currently with Acres.
Last Friday, in a separate incident, a cat was found dead in Block 115B, Yishun Ring Road, the eighth dead cat found in six weeks.
It was believed to have been thrown from the HDB block.
The Agri-Food and Veterinary Authority said last night that it was investigating the cat's death with help from the police.
Those found guilty of any unauthorised killing of an animal under the Wild Animals and Birds Act face a maximum fine of $1,000 per animal.
Under the Animals and Birds Act, anyone who neglects to supply the animals with food and/or water or subjects them to unnecessary suffering and distress is guilty of animal cruelty.
First offenders may be fined up to $15,000 and/or imprisoned for up to 18 months.
Anyone who has information regarding the death of the python can inform the Acres Animal Crime Investigation Unit at email@example.com.