Slain Texas teen Shania Gray had sexual assault charges pending against murder suspect

(CBS/AP) CARROLLTON, Texas - A Texas man has been charged with murdering a 16-year-old girl who police believe was killed to keep her from testifying at the man's sexual assault trial for raping her.

Police in the Dallas suburb of Carrollton say Franklin B. Davis, 30, of Irving, was charged with capital murder Sunday after confessing to the death of Shania Gray. Gray was last seen alive Thursday afternoon at Hebron High School in Carrollton. Her body was found Saturday in a secluded area near the Trinity River.

Carrollton police spokesman Jon Stovall told The Associated Press in an email that police believe Davis killed Gray because she was about to testify against him.

A spokeswoman for Gray's family, Sherry Ramsey, told The Dallas Morning News that Gray met Davis when she babysat his two children. Ramsey said that later, afer the teen declined many requests to babysit, Gray told her grandmother that Davis had raped her.

The crime was reported to Mesquite police, and Davis was charged with four counts of sexual assault of a child.

Ramsey said Davis had warned Gray he would kill her if she told anyone about the assault.

According to an arrest warrant, Davis contacted Gray through social media and pretended to be someone else in an attempt to get information about the sexual assault case. Davis then used a pre-paid cellphone to set up a meeting with Gray at her high school on Thursday.

Davis told WFAA-TV in a jailhouse interview that he tracked Gray down because he wanted to prove his innocence in the sexual assault case.

"I needed to get some kind of evidence, some kind of proof myself to show I did not have sex with her and that she's lying," Davis told the television station.

Davis told authorites that Gray was surpristed to see him but got into his car when he told her he wanted to talk to her about the sexual assault case.

He said he then drove her to the remote area. He told authorities she partially fell into the river after he shot her twice and asked "Why Wish?" - a nickname that Davis used. Davis then stepped on her neck till she stopped breathing, according to the arrest warrant.

"It's our understanding that Shania was killed within the hour when she was picked up from school," Stovall said.

Davis was being held Monday morning in the Dallas Count jail on $2 million bond.