OKLAHOMA CITY - A man accused of having sex with a dead prostitute hears the evidence against him. We first told you about Fulgencio Lopez's arrest in 2011. Testimony in the murder trial began Tuesday.

At times the testimony was extremely graphic. The jury heard panicked 911 calls, text messages on the phone of the murder victim, and also revealed bloody photos from the crime scene, all to bolster the case against Lopez and give creditability to the state's key witnesses.

Lopez is the john accused of picking up Lori Green, a street prostitute. They say he beat and strangled her to death and had sex with her dead body.

Brian Bates of JohnTV works to identify prostitution problems on Robinson. He's also familiar with the state's two key witnesses, both are self-admitted drug addicts and acquaintances of the murder victim. In fact, one was her boyfriend, an alleged pimp, who says they busted out the windows of Lopez's car to pull him off of Green's dead body.

But the defense argues that the state is prosecuting the wrong guy. Lopez's attorney says the witnesses gave conflicting testimonies, and evidence suggest the boyfriend and another state witness attacked Lopez and Green during sex, knocking Lopez unconscious, and killing Green.

On Wednesday, the defense is expected present its witnesses to the jury.