LOS ANGELES—A woman was charged Jan. 30 with murder and assault in connection with the death of her 4-year-old daughter, who was found unresponsive last week in a vehicle in East Los Angeles.

Maria Del Refugio Avalos, 38, was set to be arraigned Tuesday afternoon in a downtown Los Angeles courtroom on one count each of murder and assault on a child causing death.

The criminal complaint lists the victim’s name as “Mia G.” Her family identified her as Mia Gonzalez. According to the county Medical Examiner, the girl died from the combined effects of strangulation and sharp force injury of the wrist.

Los Angeles County sheriff’s deputies were summoned at 11:09 p.m. last Thursday to investigate a report of a child assaulted in the 4800 block of Civic Center Way, a couple of blocks south of the Pomona (60) Freeway, and found the girl unresponsive, according to the Sheriff’s Information Bureau. Paramedics took her to a hospital, where she was pronounced dead.

A woman later determined to be the girl’s mother was detained at the scene and subsequently arrested for suspicion of murder, sheriff’s officials said.

“The initial autopsy from the Department of Medical Examiner determined the cause of death as homicide,” sheriff’s officials said in a statement.

Ms. Avalos has remained behind bars since her arrest early last Friday.

Relatives of Ms. Avalos and the young victim told ABC7 that according to investigators, Ms. Avalos may have been driving around with the dead child for several days before she was found. They told the station Ms. Avalos left with her daughter in the car early last week.

“We were trying to contact her,” the girl’s godmother, Noemi Lopez, told ABC7. “She wasn’t responding for two days. She said she needed space, that she was going through a lot. ... She should’ve asked for help. She should’ve called me.”