A Rancho Cucamonga man is behind bars after he allegedly killed his mother, who was found dead “under suspicious circumstances” Saturday morning, officials said.

Kathryn Morales, 65, was found dead at 9:24 a.m. after deputies responded to the 9200 block of Milliken Avenue for a welfare check, the San Bernardino County Sheriff’s Department said in a news release.

“The caller had not heard from Kathryn in several days and was concerned about her,” the release said. “Upon arrival, deputies made entry to the home and located Kathryn deceased under suspicious circumstances.”

Investigators determined Morales’ 38-year-old son, Brian Morales, was “responsible for her death,” though they did not detail how Brian Morales was identified as the suspected killer nor a potential motive.

The site of his arrest was listed as also being in the 9200 block of Milliken Avenue.

Brian Morales was booked into the West Valley Detention Center on a murder charge.

He is being held without bail and is due to appear in Rancho Superior Court Tuesday morning.

Anyone with information is asked to contact Detective Brandon Becker at 909-890-4904.

To report information anonymously, contact WeTip at 800-78CRIME or wetip.com.