Investigators believe a 94-year-old woman suffering from Alzheimer's was raped by her 49-year-old caregiver, Benny Laoh.

A staff member says she saw and heard the attack, and as she walked by the victim's room she heard the victim crying.

The staff member says she opened the curtain and found Laoh on top of the victim.

"Within a very short period of time we had arrested a suspect and book him into the King County Jail on investigation of rape," said King County Sheriff's spokesman John Urquhart.

Over 150 people live at Crista Nursing Center, which has been providing care for 50 years. They say they do a background check on all employees.

We're told the victim is still living at the nursing home. Detectives are interviewing people at the care center to see if there are any more victims.

Meanwhile, Laoh is being held on $150,000 bail.

The victim was taken to Harborview Medical center as a precaution and for an examination.