The prison inmate who was allegedly murdered by "Austin Powers" actor Joseph Son has been identified, and authorities say he was a convicted child molester.

The victim has been identified as 50-year-old Thomas Graham -- who had once been convicted for committing lewd and lascivious acts on a child under the age of 14.

At the time he was killed, Graham was serving a two year sentence in Wasco State Prison for failing to properly register as a sex offender.

As TMZ previously reported, cops believe Graham's cellmate Joseph Son -- who played shoe-throwing villain Random Task in the original "Austin Powers" movie -- killed Graham in their cell on October 10.

Son is currently in solitary confinement  while prison officials investigate.

Son is already serving a life sentence for torturing a woman back in 1990.