Moscow police detained Alexei Goncharenko, a member of Ukraine's parliament, as he marched with demonstrators on Sunday in honor of slain Russian politician Boris Nemtsov, The Associated Press reports. Russian officials said Goncharenko was being questioned about his alleged involvement in a fire that broke out in Odessa last year. The fire in Goncharenko's home city killed dozens, including some Russian citizens, during demonstrations between pro-Ukraine and pro-Russia protesters. Ukraine's parliament has denounced the detention and said Goncharenko has diplomatic immunity and should be released immediately.