A few weeks ago, when soprano Malinda Haslett performed Mozart’s “Requiem” with an orchestra in Connecticut, she had a hard time staying in her seat. In rehearsals, she had found the music so pleasing that she unrestrainedly danced as she practiced, and the habit got into her bones. When she finally walked onstage in front of an audience, Haslett had to remind herself: no dancing in public.

“I had a hard time sitting still and not smiling,” she said. “It was difficult. The music was so inviting.”

Haslett will have the chance to test her sitting and singing skills again this weekend when she and three other soloists – mezzo-soprano Jami Tyzik, tenor Thomas Trotter and baritone Zheng Zhou – perform Mozart’s “Requiem” with the Bangor Symphony Orchestra 3 p.m. Sunday, April 29, at the Maine Center for the Arts.

The piece, which is modeled on the Catholic Mass for the dead, was unfinished at the time of Mozart’s death in 1791, and has maintained a mysterious history for more than 200 years. Myths arose around the work: that Mozart dictated the final measures on his death bed, that he was commissioned to write the piece by a sinister man, and that he was poisoned.

But largely these misconceptions grew out of fictional works, such as a play by Alexander Pushkin, an opera by Nikolai Rimsky-Korsakov, and eventually a stage play and the 1984 film by Peter Shaffer. Music historians know more of the truth now, but the question about which parts of the “Requiem” Mozart wrote and which were completed after his death by his student may never fully be solved.

“The most beautiful part is the ‘Lacrimosa,'” said Haslett, “and I don’t care who wrote it.”

The controversies, of course, haven’t stopped the grand and solemn piece from being a favorite among those who love choral works, such as the University of Maine Singers and Oratorio Society, both of which will join the BSO for the event. And with upwards of 100 musicians and singers on the stage, it is one of the largest music events of the season.

Haslett, who sung under the baton of Maestro Xiao-Lu Li the last time she performed Mozart, said the conductor leads the piece passionately. “He’s conscious not to make this a slow, boring piece,” she said. The result is a lighter, airier “Requiem.” Listeners can still expect eruptions of vocal and orchestral power. After all, the work is about liberating souls and spreading holy light.

For information and tickets, call 942-5555.