Authorities say the tape recovered from the apartment of Richard Davis and Dena Riley in Independence, Mo., shows the couple with Marsha Spicer in the violent final moments of her life.
Spicer's naked body was found May 15 in a shallow grave. Davis and Riley were interviewed by police last week, before the tape was obtained Friday through a search warrant, but have since fled.
"Their whereabouts are totally unknown," said Independence Police Capt. Ken Jarnagin.
Police say the video found on a TV stand in the couple's bedroom shows the 41-year-old Spicer with duct tape over her eyes and her hands secured behind her back. She is beaten, raped and sodomized as she pleads for the attack to stop.
Detectives noted that the couple had a camcorder aimed at their bed when officers interviewed them on May 17. Both denied knowing Spicer.
According to the criminal complaint filed by the Jackson County district attorney's office, police saw a notebook that contained several references to "sexual desires," "choking" and "chasing." Also, "the notebook also referred to the word 'victims' several times."
The complaint noted that Riley told investigators the notebook belonged to Davis.
Police believe the couple lured the victim to their home for a sexual encounter.
Davis, 41, and Riley, 39, are each charged with first-degree murder, first-degree assault, kidnapping, forcible rape and two counts of forcible sodomy.
Davis is on parole after spending nearly 18 years in prison for a rape and sodomy conviction in 1987.