A teenager in the US state of Texas is on trial after sexually assaulting, killing and disfiguring the body of a 15-year-old girl as part of a satanic ritual.

Jose E. Reyes, 18, allegedly engaged in consensual sex with Corriann Cervantes, 15, at a vacant apartment in southeast Houston in February before murdering her, reported The Independent.

Another 16-year-old boy who is also accused of being involved in the murder will stand trial in January.

Both of the boys have alleged that the victim had sex with them by consent.

Prosecutors, however, claimed in court on Monday (8 December) that the boys had a pact with the devil to murder and eventually disfigure Cervantes.

As part of the ritual, the boys are alleged to have carved an inverted crucifix into the victim's stomach and taken out her eyeballs after strangling her to death.

Pieces of a broken toilet lid that was used to hit the victim were also found under the victim's skin.

"Whether or not the devil was involved, what happened in that apartment was sadistic and inhumane," assistant of the Harris County District Attorney John Jordan told jurors, reported Houston Chronicle.

If found guilty, Reyes can face life sentence and would be eligible for parole after 30 years.

Reyes alleges the two boys and Cervantes took drugs on the night of the murder but they left the victim at the apartment before she died.

Reyes, a Christian, denies being a Satanist and murdering Cervantes. However in an exclusive interview with ABC13 Eyewitness News, Reyes admitted to being curious about the devil when he was younger.