Police in St Petersburg have arrested an elderly pensioner suspected of killing at least a dozen people over the last two decades. RT's Ilya Petrenko followed the traces left by the serial killer.

The news about a 68-year-old “babushka” serial killer shocked St. Petersburg earlier this week. Tamara Samsonova murdered her 79-year-old companion Valentina for allegedly not washing tea cups, cut up her body into eight parts and dumped them in different places around the neighborhood.

READ MORE: Granny the Ripper of St Pete? Body parts & book of spells expose pensioner

The locals in St Petersburg’s Frunzensky district started to find body parts in late July. After the first ones were found on the streets Monday, July 27, in a couple of days police picked up the right trail. It turned out that neighbors had seen Samsonova carrying large parcels out of the residential building where Valentina had disappeared from.

CCTV footage confirmed their testimony, and when police searched through Valentina’s apartment, they found traces of blood and a handsaw in the bathroom.

“Not even a horror movie can compare with what we're going through now. Such mayhem, you can't even imagine. Pure horror,” Natalya, a neighbour of the victim, told RT.

Another neighbor, Nadezhda, said that Samsonova “hauled out four bags.”

“She used a large saucepan to carry the head, much like the one Valya had. It's horrible,” Nadezhda told RT’s correspondent.

The dismembered body parts were found by dog owners whose pets sniffed out the remains.

One of them, Mikhail, took an RT crew on a macabre tour, showing the exact locations where bags with human remains were found.

“The bag lay over there by the bushes,” said Mikhail, recalling how his dog found the parcel and began sniffing it.

“I found out later that the contents of the bag were human remains. I had assumed someone had just thrown out some bones, maybe chicken bones, nothing more,” he told RT’s Ilya Petrenko.

Some of the body parts were found by a local pond covered with a white blanket.

“The rest were scattered all over the neighborhood. Some here, some over there,” Mikhail said.

Samsonova befriended Valentina by promising to take care of her. The killer's own flat was in another apartment building several blocks away.

The search there produced evidence suggesting that this was not the first violent crime committed by Samsonova. Further investigation led to a discovery straight out of a horror movie.

The investigators found a detailed diary she had kept for some years in three languages, the report said, in which Samsonova accounted for a dozen murders since the late 1990s.

Samsonova’s neighbor Marina told RT she was still in a “state of shock.”

“I could never have imagined her to be capable of such a thing,” she said, recalling even more frightening details from the past, the true meaning of which she is beginning to realize only now.

“I once asked her where her husband was. She answered, "Oh, it's very sad - he just left and disappeared,” Marina said, adding that she always knew that Samsonova used to rent out a room in her two-room apartment.

“I knew very well that the tenants didn't stay for long. One month, maybe two, no more,” recalls Marina, sharing that at the time she believed that the tenants preferred to leave because they “just didn't like” the elderly landlord.

Старушка-потрошительница усыпляла жертв сильным снотворным: 68-летняя петербурженка Тамара Самсонова, подозрев... http://t.co/8ZmyRwH03X — Life.ru - новости (@liferu) July 31, 2015

“As it turns out, they didn't leave at all,” Marina told RT. “And now [Samsonova] is describing how she killed this tenant, that tenant. My God.”

Neighbors have described Samsonova as an “misfit.” It was revealed that she had previously been treated by a mental health clinic on more than occasion, and been diagnosed with schizophrenia.

Once detained for Valentina’s murder, she initially said that the victim set her up and that another neighbor, a health worker by trade, assisted her in the killing, which was proved to be a lie.

Samsonova also told police that she graduated from St. Petersburg ballet school, but in reality she used to be a bellhop in a hotel.

Police say that before killing her victims she used to sedate them with powerful drugs to immobilize them.