The 24-year-old granddaughter of a Bell woman who was killed in her home has been charged with murder, the Los Angeles County Sheriff’s Department announced Monday morning.

In discussing Sarah Montoya’s arrest, sheriff’s officials also revealed the county coroner’s office determined that 64-year-old Paula Montoya died from asphyxiation by compression to the neck, sheriff’s Lt. Mike Rosson said at a news conference.

Paula Montoya was found wrapped in a blanket and in plastic when she was discovered in the bathroom of her Bell residence on July 21, three days after investigators believe she was killed, according to Rosson. She also suffered broken ribs and a contusion to the head.

Her death was ruled a homicide after investigators received the autopsy results.

“The motive, as (Montoya) stated, she just snapped,” Rosson told reporters, adding there were apparently “other things in the past” between the pair that have not been verified.

Sarah Montoya was taken into custody soon after an Aug. 2 news conference in which the Sheriff’s Department named her a “person of interest” in the investigation. A tip from the public confirmed she was in Mexico with her four children at the time, and had planned to cross the border back into the U.S., according to Rosson.

He said the granddaughter’s ex contacted Montoya, telling her she was being sought by investigators back in L.A. County.

Acting on the tip, the Sheriff’s Department alerted the U.S. Marshals Service, which in turn notified Mexican authorities, according to the lieutenant. Montoya was detained at the Otay Mesa border crossing and turned over to U.S. marshals, along with her children, who are between the ages of 1 and 9.

The kids, who were reported to be in good health, have been taken to Montoya’s mother.

Sarah Montoya was arrested Wednesday, according to inmate records. She was charged with a single count of murder and arraigned on Friday, Rosson said, without providing further details about the court date.

While talking about the relationship between the two women, the lieutenant said Sarah Montoya “was pretty much as a young girl raised by the grandmother.”

They don’t believe the younger woman had a permanent home and occasionally stayed at her grandmother’s place in Bell.

“She came and went to her grandmother’s quite often, staying for short periods of time,” Rosson said.

Sarah Montoya was believed to have been the last person to see Paula Montoya alive, according to Rosson. He stated there was no indication that the children witnessed their great-grandmother’s death.

Investigators were still conducting interviewers, but believe Montoya was the only person involved in the crime, the lieutenant said.

She had a “very minimal” criminal history that involved minor offenses, Rosson noted.

Montoya was being held on $2 million bail, according to jail records.