A preliminary hearing began this week for a Los Angeles mom accused of keeping her 11-year-old special-needs son sedated and hidden in a closet for at least three years — until horrified investigators discovered his frail, lifeless body weighing only 34 pounds.

Veronica Aguilar, 42, is charged with one count each of murder and child abuse, leading to the death of Yonatan Daniel Aguilar — once nicknamed “Chubby” — whose skeletal frame was discovered in the family’s one-bedroom home in the Echo Park neighborhood on Aug. 22, 2016, NBC 4 Los Angeles reported.

For those counts, she could face 15 years to life in prison, the outlet reported. A “special circumstance” allegation of torture — which a prosecutor said she plans to add if the case goes to trial — could make Aguilar a candidate for the death penalty or a life sentence without the possibility for parole.

Los Angeles police Detective Abel Munoz recalled the moment she first saw Yonatan inside the closet where he was hidden.

“I saw a very gaunt, frail-looking child, who at that time to me looked like a 5-, 6- or 7-year-old boy,” she testified in court Monday, according to ABC 7 Los Angeles.

Investigators grappled to understand how Aguilar and her three other children — who now range in age from 17 to 21 — kept the boy hidden in the closet in their tiny home.

Yonatan’s stepdad, Pinzon Avila, testified that Aguilar had told him she sent the boy away to Mexico for treatment — as he had special needs and behavioral problems at school, according to the report.

Avila “was hysterical, he was panting, he was hyperventilating, he was panicked” when he found out where the boy had actually been for three years, Munoz testified, according to NBC.

Avila thought of Yonatan as his son, calling him “short, chubby and playful,” the station reported. He “was a big eater,” and Avila never saw Aguilar deny him food or hit him, he added.

She tried seeking help for her son, but was frustrated because she and the boy were both undocumented, Avila said.

“She would cry a lot because she would say she didn’t know what to do,” the distraught stepdad testified.

The little boy had pressure sores often seen in elderly nursing home patients or coma patients who are rarely moved, although medical records indicate he was hyperactive, Dr. Janet Arnold-Clark, a specialist in child abuse pediatrics, testified, according to NBC.

“He was deprived of food for a very long time,” the doctor said. “Two inches in growth in 4½ years is really marked and concerning, and the only real explanation of that is that he had been malnourished for several years.”

The preliminary hearing is set to continue for several days, with Yonatan’s siblings and the coroner set to testify.

Aguilar has been held in jail since her 2016 arrest, in lieu of $2 million bail.