Harnoko Dewantoro was born on November 3, 1964, in Indonesia. He came from a prominent family, which means his family was well-known and respected in their community. In the late 1980s, he and his girlfriend moved to the United States on student visas. They started their journey in Kansas, where Harnoko attended school. After his graduation, they briefly moved to Pennsylvania before settling in Los Angeles, California.

In Los Angeles, Harnoko and his girlfriend lived in several neighborhoods. They spent time in places like North Hills, Northridge, and Westwood. They also lived in Lake Forest, which is close by. During this period, Harnoko worked in the dry-cleaning business. In January 1991, he sold his dry-cleaning shop for $100,000 to an Indian businessman named Suresh Gobid Mirchandini. However, the business was abandoned by Mirchandini after seven months, and he still owed Dewantoro money.

In January 1991, Harnoko Dewantoro sold his dry-cleaning business to an Indian businessman named Suresh Gobid Mirchandini for $100,000. Mirchandini did not fulfill his financial obligations and abandoned the business seven months later. Angered by this, Dewantoro decided to take revenge. In August, he lured Mirchandini to his car under false pretenses and drove him along the freeway. During the drive, Dewantoro pulled out a revolver and shot Mirchandini. He then buried the body in a renting home in Northridge.

In the spring of 1992, after a breakup with his girlfriend, Dewantoro contacted an Indonesian student named Gina Sutar Aswan, asking her to invest $200,000 in his business. After traveling to Los Angeles, Gina decided to back out of the deal upon returning from a vacation in Paris. Dewantoro became furious and invited her to a rented house in Brentwood, where he killed her by bludgeoning her to death. He mutilated her body by cutting off her hands, nose, and heart.

A month later, Dewantoro killed his brother, Eri Triharto Dharmawan, in a similar manner in West Los Angeles. He then moved the bodies of all three victims from their burial sites to a storage facility in Sherman Oaks. He continued to pay for the storage while living in Jakarta and falsely claimed to his mother that his brother was still using it.

On August 10, 1994, the storage unit was opened, revealing the decomposing bodies. Detective Ted Ball found checks tied to Dewantoro’s name along with his fingerprints. This led to his arrest in Jakarta in January 1995. During questioning, Dewantoro admitted to killing Gina and Eri but denied killing Mirchandini, claiming his brother was responsible for that death.

Dewantoro was charged with all three murders by an Indonesian court since there was no extradition treaty with the United States. His trial attracted considerable attention due to its brutality. He was found guilty in 1997 and sentenced to death. He spent years awaiting execution in Cipinang Penitentiary.

Dewantoro submitted two petitions for clemency that were denied. In 2019, he was allowed to leave prison on conditional parole after receiving clemency. In November 2011, a report emerged that his son, Raafi Aga Winasya Benyamin, had been murdered in Jakarta, though this claim was disputed.