Henry Rollins was commissioned to produce an album by Charles Manson, the punk rocker revealed last week. The incarcerated cult leader reportedly wrote to Rollins asking for help mixing and releasing an album of acoustic pop songs. Rollins agreed, finishing a never-released record called Completion.

Rollins revealed his Manson collaboration at an event in Los Angeles on 9 December for public radio station KCRW, playing the song for the sold-out crowd. "I can hear you all listening to your hair grow," he joked. In the 80s, Rollins was "living in [a] mouldy broom closet" at the headquarters of SST Records, the California label that released albums by the Minutemen, Sonic Youth and Rollins's band Black Flag. A lawyer representing Manson wrote to SST, asking them to help complete and release a collection of Manson's songs. Then as now, Manson was serving a life sentence for his role in the Tate/LaBianca murders.

Rollins agreed to produce the songs but a string of death threats forced SST to call off the project. In the end, the label pressed just five copies, of which Rollins kept two. The other three, presumably, are with Manson.

In a 2008 interview with NME, Rollins admitted he and Manson had been pen pals but made no mention of the album. "He wrote me a letter out of the blue once and he said, 'I saw you on MTV and I thought you were pretty cool,'" Rollins recalled. "So we corresponded a few times in 1984. I'd just tell him about what we were doing with our new record and he'd send back semi-lucid responses. He made references to the Beach Boys stealing his ideas, which sounded like sour grapes.

"At the time I was very young and having him write me letters made me feel intense and heavy," he said. "I'd always know I'd have a letter in my PO Box from him because the woman behind the counter at the post office would give you this awful look. His letters would always have swastikas on them so they were easy to spot."

While there's no sign that Completion will ever see release, Magic Bullet Records has announced a four-disc series of new Manson songs on the themes of "mankind's non-sustainable environmental conditions". The first of these, Air, was released in August.