Moscow police on Tuesday said they had detained and questioned a suspect in January's acid attack on Sergei Filin, the artistic director of Russia's world-famous Bolshoi ballet."In the course of the investigation... today, Moscow police officers delivered for questioning one of the suspects," a Moscow police statement said.Filin, a 42-year-old former dancer with the company, was splashed in the face with sulphuric acid by a masked person as he was entering his apartment building through a dark parking lot in mid-January.He spent about two weeks in a Moscow hospital getting treatment for burns to his face and having a series of surgeries on his eyes.He has since been moved to Germany for further treatment that may take months. His sight was last reported to have been partially recovered in one eye.The attack shocked the world artistic community and left one of the world's top ballet companies in crisis amid reports of furious infighting among its dancers.Several Bolshoi members have already been questioned as witnesses as part of the case.An unnamed law enforcement source told the Interfax news agency that the person detained by police was not a member of the Bolshoi.