One by one, the inmates filed into a chapel at Sing Sing Correctional Facility in Ossining, N.Y. — past a line of security officers, past a sign reading, “Open wide the door to Christ.” Under stained-glass windows, they formed a circle, introducing themselves to a crowd of visitors as composers, rappers, painters and poets. Then they began to sing.The inmates had gathered one recent afternoon for a rehearsal of “Dead Man Walking,” the death-row tale that opened the Metropolitan Opera season last week. Together, they formed a 14-member chorus that would accompany a group of Met singers for a one-night-only performance of the work before an audience of about 150 of their fellow inmates.“I feel like I’m at home,” said a chorus member, Joseph Striplin, 47, who is serving a life sentence for murder, as the men warmed up with scales and stretches. “I feel I’m alive.”Steven Osgood, the conductor, with Sister Helen Prejean. Osgood rehearsed with the inmates for more than five hours, practicing rhythm, diction and dynamics.James Estrin/The New York Times“Dead Man Walking,” based on Sister Helen Prejean’s 1993 memoir about her experience trying to save the soul of a convicted murderer at the Louisiana State Penitentiary in Angola, has been staged more than 75 times around the world since its premiere in 2000.But the opera, with music by Jake Heggie and a libretto by Terrence McNally, had never been performed in a prison until last week at Sing Sing, which is home to more than 1,400 inmates.There were no costumes or props. Chorus members, who were dressed in prison-issued green pants, had to be counted and screened before entering the auditorium, lining up by cell block and building number. Arias were sometimes interrupted by the sound of security officers’ radios.Yet the opera, with its themes of sin and redemption — and of the pain endured by victims’ families — resonated with inmates.Michael Shane Hale, an inmate, with Jake Heggie, the composer of “Dead Man Walking” and DiDonato. Working on the opera, Hale said, “reminds you not to get lost in prison.”James Estrin/The New York TimesMichael Shane Hale, 51, a chorus member serving a sentence of 50 years to life for murder, said that he often thought of himself as a monster. In the 1990s, prosecutors sought the death penalty in his case. (New York suspended the practice in 2004.)Hale said the opera, which portrays the friendship between Sister Helen and Joseph De Rocher, a death-row prisoner, had taught him to see his own humanity.“We feel so powerless; we feel so invisible,” Hale said. “It reminds you not to get lost in prison.”Not everyone at Sing Sing, a maximum-security prison about 30 miles north of New York City, was enamored. Some prisoners declined to take part in the opera because of concerns about its dark themes, including the portrayal of a prisoner’s death by lethal injection. Carnegie Hall, which helped to bring the opera to Sing Sing through the education initiative Musical Connections, said that about half of the 30 inmates in the program did not participate. (Musical Connections, which has offered instruction in performance, music theory and composition to inmates since 2009, is among similar projects nationwide that aim to help prisoners connect with society through culture.)In the prison chapel, Wendy Bryn Harmer (at the keyboard) warms up the inmate participants, including Bartholomew Crawford, front. Crawford said the opera offered hope: “It shows you’re not alone in this world.”James Estrin/The New York TimesBartholomew Crawford, 54, who is serving a sentence of 25 years to life for burglary, said he understood the concerns of his fellow inmates, but that, for him, the opera offered hope.“It shows you’re not alone in this world,” he said. “It shows you that in the darkest hour there’s light somewhere.”The idea for bringing “Dead Man Walking” to Sing Sing emerged several years ago when an inmate promised the renowned singer Joyce DiDonato, who plays Sister Helen in the Met’s production, that the men could sing the chorus parts.“This is not just theater,” said DiDonato, who has been visiting Sing Sing since 2015. “This is a story that has real consequences.”An inmate in the choir at Sing Sing. Some prisoners in the Musical Connections program declined to take part in the opera because of concerns about its dark themes, including the portrayal of a prisoner’s death by lethal injectionJames Estrin/The New York TimesFor months, the men at Sing Sing worked on an abridged version of “Dead Man Walking.” Bryan Wagorn, a Met pianist, coached them via video chat and recorded individual chorus parts for them to study. (It took several weeks for the files to clear security.) He joined Manuel Bagorro, who manages Carnegie’s program, on visits to the prison.Paul Cortez, 43, who is serving a sentence of 25 years to life for murder, worked with Wagorn to learn the score and held Saturday night rehearsals with small groups of prisoners at Sing Sing. Some were initially hesitant, unsure if the opera advanced prisoners’ rights and fearing they “might be exploited,” he said, but eventually more people started showing up.“It was daunting at first,” said Cortez, who majored in theater in college. “I did not know how I was going to get the guys in shape. But they were so diligent. They took it seriously.”From left, Sister Helen; Wilson Chimborazo, an inmate who sings in the chorus; McKinny; Joseph Striplin, another inmate singing in the production; and DiDonato.James Estrin/The New York TimesLast month, DiDonato, joined by Sister Helen, 84, visited the prison to work through the music and to get to know the participants. They discussed life in prison, morality, shame and stigma, as well as Sister Helen’s efforts to abolish the death penalty. Some inmates, saying they were still consumed by guilt about their crimes, asked about seeking forgiveness.DiDonato and Sister Helen returned last week, two days after opening night at the Met, joined by singers and staff from the Met and Carnegie Hall, and by Heggie, who offered guidance on adapting the opera for a smaller stage and reviewed some of the inmates’ Musical Connections compositions.“We’ve got each other’s backs,” DiDonato said to everyone as rehearsal got underway. “This, now, is our circle.”DiDonato, who has been visiting Sing Sing since 2015, rehearsing in the chapel with inmates. “This is not just theater,” she said. “This is a story that has real consequences.”James Estrin/The New York TimesThe Met singers introduced themselves, taking pains to remind the inmates that they were only pretending to be prison guards and police officers. (“Clemency!” a prisoner shouted, after the bass Raymond Aceto announced he was playing the role of a warden.)Sister Helen, standing among the inmates, said that there was love and trust in the room.“This is a sacred gathering,” she added. “There is no place on earth at this time that I’d rather be. We’re going to create beauty today, and you’re going to feel it.”For more than five hours, the men worked with the Met artists, under the conductor Steven Osgood, practicing rhythm, diction and dynamics in three sections that feature the chorus.They stomped their feet and clapped their hands in “He Will Gather Us Around,” a spiritual that opens the opera, which is typically performed by women and children. And they sang with fiery intensity as De Rocher confesses his murder, shortly before his execution.The Met singers and Sister Helen after the performance. Susan Graham, third from left, told the inmates that she had not fully understood the meaning of the opera until that day.James Estrin/The New York TimesThe bass-baritone Ryan McKinny, who sings the role of De Rocher, offered encouragement, telling the inmates, “This is your moment to shine.” The soprano Latonia Moore, who performs as Sister Rose, complimented the speed with which they had learned a contemporary opera. “Bravo to you,” she said.And Susan Graham, the mezzo-soprano who plays De Rocher’s mother at the Met and originated the role of Sister Helen at the premiere of “Dead Man Walking” in 2000, told the inmates that she had not fully understood the meaning of the opera until that day.Then, around 6:30 p.m., an audience of inmates and corrections officials took their seats in the auditorium, adjacent to the chapel.“The most beautiful thing in the world is a human being that does something and is transformed,” Sister Helen said in introducing the opera. “Everybody’s worth more than the worst thing they ever did.”“How you lifted your voices tonight — that spirits stays here,” DiDonato told the inmates after the performance. “It is embedded in my heart.”James Estrin/The New York TimesThe prisoners watched intensely, tapping their toes on the concrete floor and gasping when an irate De Rocher tells Sister Helen: “You’re not a nun. You’re the angel of death.” One man stood up to applaud a scene near the end when De Rocher and Sister Helen tell each other, “I love you,” shortly before he is killed. After the final rendition of “He Will Gather Us Around,” the audience offered a standing ovation.Chorus members were moved too, including Hale, who said that De Rocher’s confession “blew me away.” He hoped that the opera would inspire inmates to take responsibility for their crimes.“We have to deal with the life we have left and move forward,” he said. “That’s what we’re doing here. You have murderers singing this piece at Sing Sing.”A guard watches over the production. “You have murderers singing this piece at Sing Sing,” said the inmate Michael Shane Hale.James Estrin/The New York TimesDiDonato told the chorus members that they had created something indelible.“How you lifted your voices tonight — that spirits stays here,” she said. “It is embedded in my heart.”In their few remaining minutes together in the chapel, the prisoners and artists embraced and signed programs. Security officers wandered the pews, reminding the inmates that it was time to go back to their cells.As a guard motioned toward an exit, Cortez thanked DiDonato and the other artists, telling them, “I will never forget this moment.”Then he headed for the door. “Now,” he said, “back to reality.” More