Police said they questioned Nikolai Tsiskaridze, a principal dancer, as a witness in the assault on Sergei Filin on Wednesday.
"Employees of the Bolshoi Theatre, relatives and acquaintances of Filin, have also been questioned," they added in a statement carried by Russian news agencies.
"I was questioned as a witness, although a witness to what I don't understand," Mr Tsiskaridze told a Moscow radio station. The dancer admits that he and Mr Filin, 42, had differences of opinion over the theatre's artistic direction but he passionately denies any involvement with the assault and has condemned it as "a terrible crime which must be harshly punished".
Tsiskaridze, a flamboyant figure with flowing black hair who regularly appears as a judge on TV talent shows, last year lashed out at the Bolshoi's leadership for not giving him enough lead roles.
The Izvestia daily said Tsiskaridze had aroused the attention of investigators with his repeated criticism of the Bolshoi management.