Russia is hunting for a sinister "serial killing sex attacker" suspected of targeting children with eye squints.
Eight girls and one boy are feared to be victims in crimes dating from 1997 to 2021.
Residents of Tyumen, in the country's east, are living in fear after the naked body of the latest victim Nastya Muravyova, nine, was discovered.
She was found dead last week at Obrochny Lake — seven weeks after vanishing from a sweet shop on June 30.
Her body was wrapped in dozens of plastic bags reappeared soon after her grandmother appealed to her abductor to return her. Her clothes were in a separate bag.
Her hands were tied behind her back with an electric cable, and her mouth was covered with adhesive tape.
Both her body and her clothes were left at the shore of a lake that had been searched multiple times since Nastya vanished.
Nastya — who had a squint — was killed soon after top serial killing expert Lt-Col Evgeny Karchevsky — nicknamed Russia's 'Maniac Hunter' — was brought in to solve a mystery over disappearing children that has eluded local police in the city for decades.
Karchevsky came to fame by obtaining dozens of confessions from ex-policeman Mikhail Popkov, 57, Russia’s worst serial killer, who murdered 81 women, raping most of his victims.
On Friday, former police officer Vitaly Berezhnoy, 40, was arrested on suspicion of the rape and murder of Nastya, but he has denied killing her or the other children, the US Sun reports.
Police hunt for paedophile serial killer
Investigators believe a paedophile killer is responsible for the nine missing children.
At least nine cases in Tyumen are suspected by investigators to be linked. The majority of the children had medically-registered eye problems.
Only three bodies of the children have been found — all with similar cables.
From 1997 to 1999, three girls went missing: Lyubov Simonova, 16, Irina Kasyanova, 13, and Alyona Imamova, 12.
They were never found.
In 2001, Sofya Telesheva, 11, was murdered, and a year later Anna Bukrina, 13, half-sister of Lyubov Simonova, who had not eaten for four days before being killed, was found dead.
Both were held for a period before being strangled, police investigators say.
Sofya's was found on the lake shore where Nastya was discovered two decades later.
Between 2008 and 2010, three children went missing - Eduard Alimbayev, eight, and Anastasia Lozhkina, 12, and Anna Anisimova, 11.
They have never been found.
Police said they believe the killer is a man in his 50s who imprisons and sexually abuse his victims for several days before taking their lives.
Majority of missing kids had eye squints
A majority of the children had squints or other eye problems, even if slight, Dmitry Kiryukhin, a former scientific consultant of the Russian Investigative Committee, who earlier took part in the search for missing children, said.
"Irina Kasyanova had an eye injury, Anya Anisimova wore glasses, Anastasia. Lozhkina and Alyona Imamova had squints," Kiryukhin said.
"Nastya also had a similar feature.
"It is very likely that the maniac chooses children on this basis. But what drives him is not clear."
One theory about that the gaps of time in between children vanishing and being killed may be when the perpetrator was in jail, and checks are being made on possible suspects.
Another is that the killer may have had access to medical records.
Killer 'responded' to grandma's plea
Kuryukhin revealed that a decade ago he created a profile of the killer.
"Then he was 40-45, not convicted before, lives or lived with a woman who had a daughter, aged 11-to-13," he said.
He is suspected of working in the transport industry and having a country house where he holds the abducted children.
"If this is the same maniac, then he is now in his 50s, and even if married, he has a separate house he does not let anyone enter,” he said.
"This is where he kept the previous girls and the child who disappeared this summer, Nastya."
He believes the warped killer "responded" to Nastya’s grandmother’s plea to give her back.
"She turned to the maniac through the media..…he heard her and returned the body."
Nastya’s disappearance attracted huge publicity in Russia after a campaign led by her sister Tatyana, 18.
Their single-parent father Sergey Muravyov, 40, a porter with a previous murder conviction, initially came under suspicion in the high-profile case but he passed a lie-detector test and is no longer seen as a suspect.
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