Russian investigators have arrested a man they suspect of having robbed and murdered 26 elderly women across central Russia between 2011 and 2012.
The suspect, named as 38-year-old Radik Tagirov, is a locksmith with a previous conviction for theft, police said.
He is suspected of being the so-called "Volga maniac", who is linked to numerous crimes and killings committed in regions along Russia's Volga River.
There has not yet been any comment from - or on behalf of - Mr Tagirov.
On Tuesday, police said the suspect was being questioned and was providing information relating to their inquiries.
Russia's Investigative Committee (SK), which operates like the FBI, said in a statement that Mr Tagirov's arrest was the result of forensic research and biological analysis, which suggested that the criminal acts against the women had been committed by one individual.
It also alleged that the "pattern" of a number of the attacker's actions appeared to match the behaviour of the suspect, and that the committee had made the decision to detain him following "painstaking and systematic work".
Mr Tagirov, who investigators say lives in the Russian city of Kazan, is alleged to have gained access to the homes of the victims by posing as a utility worker, before using objects such as dressing-gown cords and electricity cables to strangle them.
Last year, police offered a reward of three million roubles (£30,000) for information leading to the arrest of the "Volga maniac" after hunting him for several years.