Ian Watkins - disgraced singer of Lostprophets - is alleged to have made royalties of up to £100,000 following his arrest for child sex offences.
The 35-year-old musician, who last month admitted to attempting to rape a fan's 11-month-old baby son and 10 other child sex offences, is believed to have earned tens of thousands of pounds since his arrest last year.
Music lawyer Craig Brookes told Wales on Sunday: "The biggest income stream will almost certainly be publishing which, even if radio play has stopped, will still be pretty big.
"So you're going to get money for plays in gyms and hairdressers and on juke boxes and all that stuff.
"The records could be earning a substantial amount. It could easily have translated to 100,000 or 200,000 extra sales. It could be easily over £100,000."
Songwriters in Britain are entitled to a cut of the profits whenever their music is played on TV, radio or online through a licensing agreement with the Performing Rights Society.
It is also thought that the increase in plays of Lostprophets' music can be contributed to TV and radio plays in reporting his crimes.
The remaining members of the now-disbanded group released a statement in which they said they are disgusted by Watkins' actions and their "hearts go out" to those affected.
In a post on their Facebook account, they said: "Our hearts go out to Ian's family, the fans and friends he betrayed, and most importantly, the victims of his crimes and others like them. We hope for justice, but also that Ian will truly take responsibility for what he's done."
Watkins will be sentenced for his crimes on Wednesday (18.12.13).
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