BANNING, Calif -

A woman whose boyfriend allegedly killed a man the couple suspected of molesting the woman's young daughter is due in a Riverside courtroom today to be arraigned on a murder charge.

Amy Lou Daniel and Brian Thomas Matheis, both 30-year-old Banning residents, are each charged with murder in the Aug. 22, 2012, slaying of Joshua Lee Fredieu.

Matheis, who was already in custody doing time for another crime, will be arraigned in September, according to court records. He is facing a special circumstance allegation of lying in wait, which makes him eligible for the death penalty if convicted. Prosecutors still have to decide whether to seek capital punishment.

On Aug. 22 last year, police responded to an apparent single-vehicle crash at Plaza and South Florida streets, and found Fredieu, who'd been shot in the head, in the driver's seat, according to Banning police.

According to a declaration prepared in support of an arrest warrant, Matheis allegedly told another inmate in the Banning jail that he shot Fredieu because he thought the Banning man molested Daniel's 4-year-old daughter.

The girl had played with Fredieu's daughter earlier that day, and when Matheis and Daniel picked her up, she was naked, having trouble urinating and her privates were irritated. When Matheis confronted Fredieu, he said he "wouldn't do that'' and had given the girl a bath, according to the declaration.

A witness alleged Daniel "was overheard trying to coach (her daughter) into stating that Fredieu must have touched (her) inappropriately ... it appeared that Fredieu had done nothing to her -- yet Daniel persisted in coaching (her) until (she) said something to the effect that Fredieu wiped her the wrong way after using the bathroom,'' the declaration states.

Daniel and an ex-boyfriend, who is the girl's father, took her to Loma Linda University Medical Center for an exam the day after the killing, but medical staff found no evidence of sexual abuse, according to police.

Matheis' cellmate told investigators that the defendant said that he and Daniel took the girl to the hospital "before I handled my business.''

The document alleges that Daniel "planned it out'' and asked Fredieu to give Matheis a ride to a convenience store. Matheis allegedly hid a gun in his sweatshirt, and once they were in the vehicle, Matheis "put the gun to the victim's head and told him, `I know what you did to my daughter''' and shot him in the back of the head, according to the declaration. The car struck a fence, knocking it over, before coming to a stop.

Matheis and Daniel allegedly fled to Minnesota but returned a short time later.

Murder charges were filed against the couple on June 25, and warrants were then issued for their arrest, according to police and court records.

Banning police Sgt. Alex Diaz told City News Service that it took time to identify the suspects because detectives initially had nothing to work with.

"This was one of your classic whodunits -- we had no information on who killed this person. It came out as a vehicle accident and it seemed odd the person died from a crash into a chain-link fence,'' he said.

He said Fredieu was shot once behind the ear. "We had absolutely nothing other than the dead body in a car,'' he said.

Detectives started doing interviews, "and from there we were able to pinpoint a couple people (as potential suspects),'' the sergeant said.

Matheis was serving a nine-year prison term for an unrelated domestic violence case that happened after the killing and was re-arrested on the homicide charge, according to police. He is scheduled to be arraigned Sept. 11 at the Riverside Hall of Justice.

Daniel was arrested Aug. 13 and was booked into the Larry D. Smith Correctional Facility in Banning, where she's being held in lieu of $1 million bail.