A missing Alabama girl who was found dead last month was beheaded after witnessing her grandmother’s fatal stabbing, an investigator testified during a preliminary hearing this week.

According to AL.com, Madison County investigator Stacy Rutherford said Israel Palomino, 34, and Yoni Aguilar, 26, murdered Oralia Mendoza, 49, and her granddaughter, Maria Lopez, days after doing a drug run with Mendoza.

On June 2, Palomino, Aguilar, Mendoza, and a second woman reportedly picked up a quarter of a kilogram of meth in Norcross, Georgia—a trip that, for some reason, led Palomino to believe that a setup was afoot.

READ More: Body of 13-year-old girl found, grandmother missing and in extreme danger: Police

Rutherford said it was Mendoza and the second woman who were associated with the Sinaloa Cartel. WAFF reported that the grandmother was once romantically linked to Palomino and that she was in a relationship with Aguilar at the time of her murder.

On June 4, Mendoza was reportedly told she would be taken somewhere safe. According to the investigator, Aguliar said he and Palomino drove Mendoza and the 13-year-old to Moon Cemetery, where an argument ensued regarding the recent drug buy. Aguliar reportedly said the argument turned violent when Palomino fatally stabbed Mendoza outside the car.

Rutherford testified that Aguliar claimed Palomino forced him to decapitate Lopez by moving his arm back and forth in a sawing motion as he held a knife. The investigator also revealed that the slain 13-year-old was special needs; WAFF indicated she was on the autism spectrum.

Aguliar reportedly told police that they had to kill Lopez because she witnessed her grandmother’s murder. The grandmother was Lopez’s main guardian at the time. The news station reported that Palomino had denied making Aguliar kill Lopez.

READ More: Exclusive: Police say body discovered is likely Oralia Mendoza; granddaughter’s body found last week in suspected murder

AL.com reported that a farm boy discovered Lopez’s body near the cemetery on June 7. Shortly after police provided the public with a description of the unidentified body, the teen’s mother came to the station and claimed the body might be her daughter.

WAVY reported it was after authorities told Aguliar that cellphone pings placed them at the scene of the crime that he revealed what transpired and led them to Mendoza’s body at the cemetery.

Investigators reportedly recovered the murder weapons under Palomino and Aguilar’s mattresses. Moreover, Rutherford alleged that blood was located in Palomino’s car.

Aguliar’s murder case will go before a grand jury. Meanwhile, Palomino’s preliminary hearing is scheduled for later this month.

[Featured image: Oralia Mendoza, Maria Lopez/Madison County Sheriff’s Office]