A 13-year-old Huntsville girl was beheaded after she witnessed her grandmother assaulted with a knife and left to die on the ground in a cemetery, court testimony revealed.

The grandmother was associated with the Sinaloa Cartel, a drug-trafficking organization, a Madison County sheriff's investigator testified today.

Just days before Oralia Mendoza and her granddaughter, Mariah Lopez, were killed, Mendoza and three others went to pick up a batch of methamphetamine, Investigator Stacy Rutherford told a judge. After one of her drug cohorts became suspicious, the situation turned deadly.

Israel Palomino, 34, and Yoni Aguilar, 26, are charged with two counts each of capital murder in the slayings of Mendoza and Lopez.

Aguilar was in Madison County District Court on Thursday for a preliminary hearing. District Judge Claude Hundley ruled prosecutors have enough evidence to send the case to a grand jury. In a statement to investigators, Aguilar, who was Mendoza's boyfriend, confessed and also implicated Palomino, according to the sheriff's office.

It was June 2 when Palomino, Aguilar, Mendoza and a woman named Leticia Garcia went to pick up a quarter kilo of meth in Norcross, Georgia, a small city northeast of Atlanta, authorities said. Something apparently went wrong during the trip, Rutherford told the court. It was Mendoza and Garcia who were tied to the cartel, and Palomino thought there might be a setup, the investigator testified.

During the early morning hours of June 4, Mendoza was told she and Lopez would be taken somewhere safe.

Instead, Rutherford testified, Palomino and Aguilar drove the woman and her granddaughter to Moon Cemetery on Cave Springs Road. Mendoza and Palomino got out of the car and argued about the drug buy, according to Aguilar's account, which Rutherford recounted in court.

The argument escalated, and Aguilar told police Palomino killed Mendoza. Authorities have said her cause of death was sharp force trauma caused by a knife.

Because Lopez was a witness, the suspects took the girl to a secluded area on nearby Lemley Drive, Rutherford testified. In his statement, Aguilar said Palomino forced him to kill the girl.

Aguilar told investigators he was holding the knife when Palomino came up to him and moved his arm back and forth in a sawing motion. Lopez was beheaded, Rutherford testified.

Aguilar told investigators that Palomino forced him to kill the girl.

"He said he was fearful of Israel," Rutherford testified.

It was three days later, on June 7, that the sheriff's office started investigating. A farm boy found a body on the Lemley Drive property. The sheriff's office released to local press a description of the clothes on the body, and it took less than 30 minutes for a woman to show up at sheriff's headquarters.

The woman said she was the mother of Lopez and Mendoza's daughter. She told authorities the body might be Lopez.

It took about a week for forensic scientists to positively identify the body as Lopez. By then, Aguilar and Palomino were in custody. After Aguilar confessed, authorities found Mendoza's body at the cemetery on June 15.

Aguilar and Palomino's cellphones pinged in the area during the time of the killings, Rutherford testified. Investigators also recovered two knives, believed to be the murder weapons. One was found under Aguilar's mattress; the other was under Palomino's mattress, Rutherford told the judge. Additionally, blood was found inside Palomino's car, the investigator testified.

Palomino's case was set for preliminary hearing Monday, but the court appearance has been continued.

Lopez was a Challenger Middle School student. Rutherford testified today that the girl was special needs. Thursday's hearing was emotional. Lopez' family cried as the investigator recounted the details of the case.

Updated July 15 at 8:59 p.m. to show Palomino's hearing is continued.