* Verdict in acid attack trial due on Tuesday
* Prosecutors want dancer jaieldfor nine years
* Open letter says punishment must be proportionate
By Maria Tsvetkova
MOSCOW, Dec 2 (Reuters) - Performers at Russia's Bolshoi Theatre made a last-minute plea for leniency on Monday for a dancer accused of ordering an acid attack on its artistic director, praising his "wonderful human qualities" and saying he was incapable of such an act.
A judge is due to pronounce a verdict on Tuesday in the month-long trial of former soloist Pavel Dmitrichenko that has shone a spotlight on bitter rivalries behind the scenes.
State prosecutors have asked for a nine-year prison term but he could still be jailed for up to 12 years if convicted over an attack that nearly blinded the Bolshoi ballet's artistic director, Sergei Filin.
The month-long trial of Dmitrichenko and two alleged accomplices has tainted the reputation of one of Russia's most prominent cultural symbols.
"In the open trial, the public has heard absolutely no evidence confirming his guilt," dozens of performers and other staff at the Bolshoi said in an open letter published on the website of the daily Izvestia newspaper.
Dancer Natalya Vyskubenko said it was signed by about 150 people.
A masked assailant splashed acid in Filin's face when he was returning home late in the evening from the Bolshoi last January, leaving him writhing in pain. His eyesight remains impaired after more than 20 operations.
Dmitrichenko, 29, has acknowledged that he wanted Filin roughed up and had given co-defendant Yuri Zarutsky the go-ahead to hit him, but has pleaded not guilty to ordering an attack involving acid. Zarutsky has said the use of acid was his idea and that he had not told Dmitrichenko of his plan.
Citing what it called Dmitrichenko's "decency, flawless professionalism ... and wonderful human qualities," the letter said those who knew him found it "absolutely unacceptable (to say) he could have inspired and ordered a crime that was committed in such a savage way."
"The judge's decision in this case must be proportionate to the real guilt of each participant - or lack thereof," it said.
Prosecutors have asked the court to sentence Zarutsky to 10 years in prison and Andrei Lipatov, who is accused of driving Zarutsky to the scene, to six years.
The prosecution said Dmitrichenko was motivated by a conflict with Filin, 43. In court last week, prominent former Bolshoi dancer Nikolai Tsiskaridze told the court he had denied roles to both Dmitrichenko and his girlfriend, a ballerina.
Defence witnesses have attacked Filin's character, portraying him as an imperious hothead and Dmitrichenko as a champion of others who felt slighted by the artistic director, who has considerable power to make or break careers.
(Writing by Steve Gutterman)