On the evening of August 28, 1962, the air at the Ranchero Palms Apartments was rent by loud classical music and screams coming from the de Kaplany apartment. When police arrived, they found his wife had been horribly tortured. Kaplany had tied her to a bed, dowsed her body with sulfuric and nitric acids, and mutilated her body with a knife. She suffered third degree corrosive burns over 60% of her body, and her genitals were almost completely obliterated. De Kaplany told police at the scene that Hajna had been unfaithful to him, and he wanted to destroy her beauty. One ambulance worker was treated for burns sustained from touching her body. Hajna de Kaplany fought desperately for her life for 33 days before succumbing to her burns.
As recounted by San Francisco Chronicle reporter Carolyn Anspacher in her 1965 book, The Trial of Dr. De Kaplany, the 1963 trial was a sensation. De Kaplany pleaded not guilty by reason of insanity, claiming that he suffered from multiple-personality disorder and that the sadistic crime was committed by his alter ego, "Pierre de la Roche." He was convicted of first-degree murder, but his bizarre behavior before and during the trial apparently prompted the jury to sentence him to life imprisonment, rather than the death penalty.
De Kaplany was granted parole in 1975 after serving less than 12 years, in a controversial decision marked by accusations that gruesome post-mortem photographs of Hajna de Kaplany were removed from his file prior to review by the California State Parole Board. The parole board then allowed de Kaplany to travel to Taiwan as a medical missionary. Upon his arrival in Asia, he publicly claimed that the California state authorities had no jurisdiction over him there, then dropped out of sight. He re-surfaced briefly in Munich, Germany in 1980, where a hospital fired him from a staff position after his crime was made public there. After that, his whereabouts were a mystery to California authorities for over 20 years. In 2002, reporters for the San Jose Mercury News located the 75-year-old de Kaplany — now married for a second time — and interviewed him at his home in Germany. In the intervening years, he had become a naturalized German citizen, making it impossible to extradite him for the parole violation.
The de Kaplany case has often been cited by capital punishment advocates as a glaring example of parole board leniency. It should be noted, however, that life without parole was not available as a sentencing option in 1963 California. Many crime observers at the time believed that the murder of Hajna de Kaplany was the most horrible single murder in California — and perhaps in American — history. It is almost certainly the only murder on record in which acid was used as the murder weapon, rather than a means of disposal.