Djalilov's remains were found at the blast site and traces of his DNA were also discovered on a bag containing a bomb at another metro station that was successfully defused, investigators said.
Putin, speaking from Constantine Palace in St. Petersburg, said investigators were looking into whether the explosion was a terror attack or if there might have been some other cause.
There has been no claim of responsibility.
The bomb went off on a train under Russia's second-largest city on Monday. Questioning of family and neighbors indicate the alleged suicide bomber had worked to fix cars in St. Petersburg. Thousands of miles to the east, authorities in the former Soviet republic of Kyrgyzstan identified one suspect as a Kyrgyz-born Russian citizen.
But the incident poses a range of major problems for Russian Federation and the broader region, especially ahead of the World Cup being held in the country next year.
The six come from former Soviet Central Asian republics.
"When the owner let (the apartment) I asked her and she said he was a decent guy and that I should call her if he makes noise".
A police officer with her police dog secures an area at Tekhnologichesky Institute subway station in St. Petersburg, Russia on Tuesday.
Those hurt include citizens of Belarus, Kazakhstan and Uzbekistan, as well as Russians from 13 different regions, according to the Saint Petersburg authorities.
They said Djalilov flew back to Russian Federation on March 3 after a visit to the country.
Residents have been bringing flowers to the stations near where the blast occurred.
Russian President Vladimir Putin told security officials from a regional alliance Wednesday that the subway bombing underlines that terrorism's threat isn't subsiding. Many were students heading home Monday after classes on one of the city's busy north-south lines.
Russian ground transport has also been hit by extremists before, including in the Moscow metro and the Domodedovo airport, where a blast claimed by Islamic insurgents killed 37 people in 2011. "Global jihadism spread to Central Asia, even if the number of terrorist attacks in this region is much lower than in the North Caucasus and the rest of Russian Federation so far", Uwe Halbach noted.
In Wednesday's sweep in St. Petersburg, law enforcement agencies arrested seven Central Asian migrants who are suspected of acting as recruiters for the Islamic State and the al-Qaida's branch in Syria.