In August 1991, Dawn Sanchez, a prostitute, was last seen leaving the Four Seasons Motor Lodge in Los Altos, California with her boyfriend, Bernardo Bass. Her disappearance was not reported until October of that year.

Bass was arrested and charged with kidnapping and murder in October 1991, but the charges were dropped for lack of evidence. He was arrested again in 2007 when the case was reopened, and in 2009, he pleaded no contest to involuntary manslaughter in Sanchez's case.

According to a witness, William Alcorn, he had traveled with Bass and Sanchez to a vacant lot near the Twin Creeks Softball Park in Sunnyvale, California, where he heard the couple fighting, then heard a gunshot. Bass was described as a jealous and controlling boyfriend who had allegedly broken into Sanchez's apartment and slashed the tires of other men interested in her.

The Grand Prix car in which Sanchez and Bass were last seen was never found, and Bass's sister initially claimed she had sold it on his behalf. She later recanted this story, but the car remains missing. Sanchez's body has also never been found, but cadaver dogs indicated the presence of human remains in Bass's home.

Bass's plea of no contest to involuntary manslaughter suggests he acknowledged the existence of sufficient evidence to convict him if the case went to trial. He was sentenced to six years in prison, with credit for time already served.

The circumstances surrounding Sanchez's disappearance suggest foul play, and her case remains unsolved. Some agencies report the date of her disappearance as September 20, 1991.