CALABASAS – A former employee of an upscale senior home was arrested Thursday for allegedly assaulting a resident before his death.

Cesar Ulloa, 20, was among four former employees of Silverado Senior Living arrested on suspicion of elder abuse, said Los Angeles County sheriff's detectives.

Sheriff's detectives described Ulloa as the ringleader of the group, which allegedly harassed and abused residents at the home that specialized in caring for seniors with dementia and Alzheimer's.

The 11-month investigation into the former workers began after an anonymous tipster who worked at Silverado told authorities that a man who died at the home was a victim of foul play.

Detectives exhumed the body of 80-year-old Elmore Kittower in November and interviewed dozens of employees, residents' family members and others. Sheriff's officials said there is now evidence that Ulloa assaulted Kittower before his death and had been abusing him for months.

It was not immediately clear whether the alleged abuse contributed to his death. The coroner's office said Kittower's file was sealed for security reasons Thursday night and could not release his cause of death.

Sgt. Bill Cotter of the sheriff's homicide would not say how many alleged victims are involved or describe the alleged abuse because prosecutors are considering which charges to file against various defendants in the case.

The man's widow, Rita Kittower, said the home initially told her that her husband died in his sleep and had no idea he may have been abused.

“When I heard what they did to him, it just about killed me,” she said. “I can't get it out of my mind. It's a sore that won't heal.”

The other former workers arrested Thursday include Luis Arrelleano, 21, Juan Soto, 21, and Maria Gomez, 34. An attempt to reach attorneys for the suspects was unsuccessful Thursday night.

A spokesman for Silverado, Mark Mostow, said the company has a zero tolerance for mistreatment of residents.

Information from: Los Angeles Times, www.latimes.com