“The person is being questioned at the moment,” Maxim Kolosvetov, a police spokesman, said by phone Tuesday. “Investigators have 48 hours to decide whether to arrest him.”

Police later issued a statement saying they had searched the home of Bolshoi ballet soloist Pavel Dmitrichenko in connection with the investigation. It wasn’t clear if Dmitrichenko, who’s been with the Bolshoi since 2002, was the person in custody.

Police last month said they were probing the possible involvement of Bolshoi ballet dancers and employees in the Jan. 17 assault on Filin, 42.

The investigation has fanned rivalries at the historic theater, which was founded in 1776 by Catherine the Great. Nikolai Tsiskaridze, the principal dancer, accused management of waging a Stalin-era witch-hunt against him.

“They are organizing meetings against me and forcing people to sign letters against me,” Tsiskaridze, 39, said in an interview with the BBC that was posted on the its website Feb. 8.

The previous week, Bolshoi General Director Anatoly Iksanov told billionaire Mikhail Prokhorov’s Snob magazine that he believed Tsiskaridze was behind the Internet release of gay pornographic photos that led to the resignation of Filin’s predecessor, Gennady Yanin, in 2011.

Swan Lake

In the Snob interview, Iksanov, 61, didn’t accuse Tsiskaridze of ordering the attack on Filin, though he did blame the Georgian-born dancer for fostering a culture of animosity within the theater by openly seeking Filin’s job.

The Bolshoi’s spokeswoman, Katerina Novikova, last month said the theater’s lawyers were studying the possibility of suing Tsiskaridze for reputational damage.

Filin has said that his mobile phones were tampered with and his email and Facebook Inc. accounts hacked in the days before a masked assailant threw acid at his face as he arrived at his home in the Russian capital.

Tsiskaridze has repeatedly denied involvement in the attack, though he accused Filin of seeking to turn one of his pupils against him by offering her a part in Swan Lake if she stopped taking lessons from him.

Filin is still being treated in Germany and plans to return to work by the summer, Novikova, said on state-run Rossiya 24 television Tuesday.

“That the police have a suspect now is great news for the Bolshoi,” Novikova said.