"We believe that investigators still have a lot of work to do to establish all of the facts," Filin's lawyer Tatyana Stukalova said in an interview on Rossiya state television.
The Bolshoi's general director, Anatoly Iksanov, has accused veteran principal dancer Nikolai Tsiskaridze of inspiring the attack. Tsiskaridze, a long-time critic of the theater's management, has denied the allegation.
Dmitrichenko's girlfriend, Anzhelina Vorontsova, is coached by Tsiskaridze.
Dmitrichenko and Tsiskaridze are both followers of legendary choreographer Yuri Grigorovich, who led the Bolshoi dance company for three decades. He was forced out in 1995, but remains on the Bolshoi staff.
A string of successive artistic directors tried to bring new energy and a more modern repertoire to the Moscow theater, only to face opposition from dancers and teachers who remained devoted to Grigorovich and his ballets.
Filin, who took up his post in March 2011, was seen as capable of bridging the gap. He was a veteran of the Bolshoi, where he danced from 1989 until 2007, and later served as artistic director of the Stanislavsky and Nemirovich Theater, Moscow's second ballet company.
Filin was instrumental in bringing a young Vorontsova to Moscow to study and had hoped she would stay to dance for him at the Stanislavsky. Instead, she joined the Bolshoi.
AP writer Vladimir Isachenkov contributed to this report.