They left flowers at the place where Samba Lampsar Sall was gunned down on April 7.
The 28-year-old Sall was killed as he emerged from a nightclub, where he and other students had been holding an annual faculty party.
Prosecutors quote witnesses as saying Sall's murderers used a shotgun decorated with a Nazi swastika symbol.
The Senegalese government demanded on April 8 that Sall's killers be "prosecuted and severely punished."
St. Petersburg has been the scene of several attacks and killings on foreigners. In most instances, the culprits were skinheads.
(NEWSru.com, AFP)