The mother of a fourth suspect accused of abusing a 16-year-old boy who was allegedly shackled and tortured in a couple's Northern California home said her son occasionally visited the home but never saw the boy.

Alice Waiters, whose 29-year-old son Anthony Waiters was arrested Tuesday, told The Associated Press that her son sometimes watched football games at the Tracy home of Michael Schumacher and Kelly Layne Lau. She said their families barbecued July 4 at her home, but that neither she nor her son ever saw the boy.

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"This is shocking. I know my son, the child that I raised, and he couldn't have done something like that. This is a bunch of trumped-up charges," said Waiters.

Police say that for more than a year, Schumacher, 34, and Lau, 30, held the boy against his will and, along with the teen's one-time guardian, Caren Ramirez, 43, beat him, denied him food and sometimes kept him chained to the fireplace or a heavy table. Schumacher, Lau and Ramirez each have been charged with multiple abuse and related charges.

The boy ran away from the house last week by jumping over a backyard fence and finding help at a local fitness center. The boy was covered in soot, looked years younger than his age and was bleeding from where he was still shackled around his ankle.

Anthony Waiters was booked on suspicion of torture, conspiracy, child endangerment, corporal injury to a child and false imprisonment charges. No further information was released about his arrest, with police citing a judge's gag order in the case.

"I'm not saying that boy wasn't abused," Alice Waiters said. "But he wasn't abused by my son."

She said she and her son were interviewed by police last week and told authorities they never saw evidence of abuse at their neighbors' home.

"I would say Michael seemed to be quiet and respectful. Kelly on the other hand, her attitude is questionable," Alice Waiters said. "She gives off the impression of living a rough-type life."

She said Ramirez joined the couple about 18 months ago and she would often wave at her, "being neighborly." Alice Waiters said she never wondered what Ramirez was doing there. "I don't get into anybody's business," she said.

Anthony Waiters was being held in the San Joaquin County Jail on $685,000 bail. He was scheduled to make his first court appearance on Thursday.

Schumacher, Lau and Ramirez each are being held in lieu of more than $2.2 million bail at the San Joaquin County Jail. They have yet to enter pleas and are due back in court Jan. 5. Calls to their attorneys were not immediately returned.