The killer stole the women's lives and whatever meager savings the women had in their homes.
For eight years, starting in 2002 or so, elderly women in Russia's Sverdlovsk Oblast were being singled out and found brutally murdered in their homes.
The women - 17 in total - were found in pools of blood with their skulls bashed in from an axe or hammer, the outlet KP reports.
They were all robbed of very little money, and in three instances, their homes were set ablaze to hide evidence of the slaughter that had taken place inside, authorities said.
For years, authorities searched for a suspect whom they believed was a man, with no success.
Then, in 2010, a bombshell arrived.
The terrifying killer police were looking for was not a man but a woman, Irina Gaidamachuk, who became known as Russia's most notorious female serial killer, The Times reports.
"How could someone kill a frail and defenseless old lady in such a savage way?" said Elena Golovenkina, whose mother was killed in 2002 when Gaidamachuk repeatedly struck her over the head with a statue of Vladimir Lenin, according to The Times.
Arrested in 2010 at age 39 when one of her victims managed to flee, the married mother of two from Krasnoufimsk in Sverdlovsk Oblast -- nearly 800 miles east of Moscow -- told police she bludgeoned the women to death while robbing them.
"She's an exceptionally brutal woman," said one detective who worked on the case, according to The Times. "I was convinced we were dealing with a man. After all, how could a woman smash a head with 24 blows?
"For a while, when witnesses began talking about a woman, we even suspected a man dressed up as a woman," the detective said.
"She said she'd lost count of how many people she'd killed after the 10th murder. She's very coldblooded but also charming and even attractive. She even tried flirting during our questioning."
Gaidamachuk usually gained her victims' trust by posing as a social worker, according to 66.ru.
"The accused looks for elderly women, finds a way to get into their apartment, drinks tea in their kitchen or asks for water," the prosecutor said in 2012, 66.ru reported. "After that, when the victim turns away, she strikes them on the head several times with a blunt object. She covers their head with one or more pillows. She takes only money, leaving gold and valuables. All the crimes have the same style and the same scenario."
In one instance, when Gaidamachuk was unable to find any money to rob, she allegedly stayed overnight with one of her dead victims, covering the elderly woman's battered face with a pillow, according to The Times.
Gaidamchuk allegedly used the money she stole to buy alcohol, according to RGRU.
Convicted of 17 counts of murder and one count of attempted murder, in June 2012 she was sentenced to 20 years in prison.
Most of the crimes were committed in Krasnoufimsk; though she committed similar ones in Yekaterinburg, Serov, Achit, and Druzhinino, according to Tass, Russia's news agency.
Victims' loved ones wished justice had come sooner.