AFAIK, Obama and Lugar were detained in Perm as part of an investigation against a Russian company involved with a US government program to dismantle a derelict Soviet nukes. There was an alleged kickback and espionage scheme, agents in charge had no idea these guys are US Senators. They thought Obama and Lugar are some American businessmen or CIA guys so they wanted to interrogate and examine their baggage to find what they got from a Russian CEO. Once in custody, Obama used his phonecall to inform a US consulate in Yekaterinburg or Moscow Embassy so they were free in a hour to avoid a diplomatic scandal.
Also, Obama and Lugar illegally used USAF jet for their fight so Russians detained aircrew and seized a plane to search it to save face after a major screw-up.