When Manic Street Preachers' lyricist Richey Edwards disappeared from his room at the Embassy Hotel in London's Bayswater district on the night of 1 February 1995, he set in motion one of rock 'n' roll's most enduring mysteries. He had been due to fly with the band's guitarist and singer James Dean Bradfield to America the following day for promotional duties, and like the Joy Division frontman Ian Curtis, who took his own life on the eve of an American tour, he may have felt that the prospect of transatlantic success in some way compromised his artistic principles. But although his passport was found back at his apartment in Cardiff, and his car found abandoned a fortnight later at the Aust motorway services overlooking the River Severn, Edwards himself has never been seen since.

In his absence, a host of myths and rumours has sprung up around the troubled pop star, with supposed sightings of him in places as far afield as the Indian state of Goa and Fuerteventura in the Canary Islands. As with Elvis, fans' imaginations have proven stubbornly unresponsive to the most obvious explanation, which is that Edwards probably jumped from the Severn Bridge to his death.

Sadly, his parents have been denied even the solace of knowing for sure what happened to Edwards, all human remains subsequently found in the area having been scientifically proven not to be his. Although in 2002 his parents declined the opportunity to have him declared dead on the seventh anniversary of his disappearance, last week they finally conceded he was unlikely to be alive.

Born into a mining family in the South Wales town of Blackwood, Richey Edwards was an intelligent outsider in the classic rock-hero tradition. His adolescent literary tastes stretched to the usual proponents of existential angst, from Rimbaud, Kafka and Dostoyevsky to Salinger, Golding and Ballard, and he was particularly drawn to the poetry of Sylvia Plath. He earned three "A" grades at A-level, and went on to secure a degree in Political History at the University of Wales in Swansea, where he became close friends with bassist Nicky Wire (real name Jones), who would form the Manic Street Preachers with Bradfield and the drummer Sean Moore. Initially taken on as the band's driver and roadie, Edwards was co-opted as rhythm guitarist after collaborating with Wire on artwork and lyrics for their first single, "Suicide Alley".

His musical prowess was minimal, however, with his amplifier often being turned down on stage; but he brought to the group a decisive charisma and intellect that helped establish its direction and reputation. Unusually, songwriting duties were split within the band, Wire and Edwards collaborating on the lyrics, which were then set to music by Bradfield and Moore.

The band's emphasis on style and sensation over music was received with some suspicion by the British music press, and when, backstage after a May 1991 show in Norwich, the NME journalist Steve Lamacq cast doubt on their commitment, suggesting they weren't "for real", Edwards produced a razor blade and carved the phrase "4 REAL" into his forearm during an interview, requiring 17 stitches at the local hospital. Taken in the immediate aftermath of the self-mutilation, the resulting photograph by Ed Sirrs of the bloody legend became one of rock's most recognisable iconic shots, its cachet further multiplied following Edwards' disappearance.

It was not the first time he had cut himself: since childhood he had taken psychological refuge in self-harming, usually through lit cigarettes, and he had also exhibited symptoms of anorexia nervosa.

In the immediate wake of the incident, however, the music industry became more interested in the band, and a deal was quickly signed with Sony Records, who released the first Manics LP, the double album Generation Terrorists, in 1992. Its songs each came with an illustrative quote from poets and philosophers as diverse as Plath, Larkin, cummings, Confucius, Nietszche and Ten Bears, a Native American thinker, but while the band's own lyrics, such as "Rock 'n' roll is our epiphany/Culture, alienation, boredom and despair" promised much, The album reached No 13, but while the follow-up, Gold Against The Soul, reached the Top Ten.

Their third album The Holy Bible (1994) came clad in a triptych by the painter Jenny Saville which reflected both the antagonistic tone of Edwards' lyrics and the album's fixation with the human body, the fat woman in the portrait contrasting starkly with his anorexia anthem "4st 7lb", which contained the sentiment, "Four stone seven, an epilogue of youth/Such beautiful dignity in self-abuse". Elsewhere, he wrote about death camps, political correctness and the erotic appeal of demagoguery, but the overwhelming impression was of misanthropy, awash with disgust expressed with an almost puritan fervour.

It is still regarded by many fans as the band's masterpiece, and charted even higher than before. But it would be Edwards' final recorded work with the group. That same year he checked into a Cardiff psychiatric hospital, and then into The Priory, for treatment. He played his final show with the Manics at London Astoria on 21 December 1994, after which the band were set to gather their resources for an assault on America, for which Edwards and Bradfield should have laid the groundwork with their promotional visit. When, following Bradfield's failure to get any response, Edwards' hotel room was unlocked by the Embassy Hotel management on the morning of 2 February 2 1995, it was found to contain little beyond the guitarist's clothes and a sheaf of lyrics.

I know I believe in nothing but it is my nothing

Richard James Edwards, guitarist and lyricist: born Blackwood, Gwent 22 December 1967; declared legally dead 23 November 2008.