The suspect in the suicide bombing on the St Petersburg metro that killed 14 people has been described as a "quiet, decent guy" by his neighbours.
Akbarzhon Jalilov had rented an apartment in north-eastern St Petersburg a month before the blast, around 20km from the site of the explosion.
"The apartment was always silent," said a resident of the same staircase at the building, who gave her name as Margarita.
"When the owner let the apartment she said he was a decent guy, and that I should call her if he makes noise."
"But I never heard any music playing. Maybe he turned on the TV once."
Jalilov was born in 1995 in Kyrgyzstan and held a Russian passport, and had recently returned from a trip to his home city of Osh in southern Kyrgyzstan.
Osh is part of the Fergana Valley, a fertile strip of land that straddles Kyrgyzstan, Uzbekistan and Tajikistan and is mainly populated by ethnic Uzbeks.
It has a tradition of Islamist radicalism, and hundreds of people have left the area to join Islamic State in Syria and Iraq.
Security officials raided the apartment on Thursday (local time) and a witness present during the search said she saw belongings packed into bags and boxes, and household containers with an unidentified powder inside.
The Investigative Committee, the state body leading the investigation, said footage from security cameras near the same building showed Jalilov leaving, carrying a bag and a rucksack.
Jalilov's parents, who said they had not seen their son for a while, were due to fly into St Petersburg on Thursday, and a witness at Pulkovo airport reported heavy security.
A middle-aged man and woman were escorted away after the flight arrived.
Authorities would not confirm whether the couple were Jalilov's parents but the woman, in response to a Russian TV reporter's question, said she did not believe her son was the bomber.