A 54-year-old Hilo man was sentenced Friday to 30 years in prison for the 2022 abduction and sexual assault of a 15-year-old girl who was taken from a West Hawaii beach to his Hilo property and shackled inside a bus.
Kona Circuit Chief Judge Wendy DeWeese also ordered Duncan Mahi to serve a mandatory minimum of 20 years in prison.
Mahi negotiated a plea deal Dec. 31 with the state. In exchange for his no- contest plea to one count of first-degree sexual assault and first- and second- degree kidnapping, the state dismissed the eight remaining counts of his 11-count indictment.
Those dismissed counts include first- and third- degree sexual assault, methamphetamine trafficking, two counts of first- degree robbery and two counts of first-degree terroristic threatening.
The girl told police she was with her boyfriend, also 15, at Anaehoomalu Beach on Sept. 16, 2022, when Mahi robbed them of their cellphones and $50.
She also related how Mahi forced her to zip-tie and tape her boyfriend’s legs and hands together, gag him with his own shirt and cover his head with a towel and tape it. Mahi then kidnapped her at knifepoint and led her to his car. He forced the girl to smoke meth, made her perform sexual acts on him and fondled her as he drove to Hilo. He took her to his property where he shackled her inside a bus.
The girl convinced him to take her to get some food, and she managed to escape from Mahi’s grasp the following day at 11:26 a.m. Sept. 17, 2022, while in an alleyway near a Hilo restaurant, with the help of good Samaritans.
Her captor claimed he was the girl’s father, but witnesses recognized the girl from the Maile Amber Alert. One witness took a photo of the car as he fled.
Mahi was arrested at 2:51 p.m. Sept. 17, 2022, in Hilo.
DeWeese told Mahi before meeting out his sentence: “Your actions devastated the lives of two young people and their families, and cut our community to its core. …
“You victimized two young people in a particularly cruel way, in a way that they will probably never fully recover, in a way that will likely haunt them and their families and their loved ones forever.”
DeWeese told Mahi that the victims “submitted to the state to make you a plea offer to allow you to avoid the likelihood of life in prison.”
Deputy Prosecutor Kaua Jackson asked the court for consecutive sentencing.
DeWeese sentenced Mahi to consecutive sentencing on the two kidnapping charges. First-degree kidnapping carries a 20-year sentence, while the second- degree charge has a 10-year term, for a total of 30 years.
DeWeese handed down a 20-year sentence for the first-degree sexual assault to run concurrently with the 30-year sentence.
(Mahi was also assessed a fee of $1,515 to go to the Crime Victim Compensation Fund.)
The judge told the 54- year-old he poses “an unacceptable risk of re-offending unless you are confined for an extended period of time,” citing his violent criminal history.
She told him his behavior was “planned and predatory and not spur-of-the-moment, driven by your drug use. You had zip ties. You had tape. You had shackles.”
DeWeese added that many in the community abuse drugs, “but they do not behave in the way you did. They do not go out and sexually assault and kidnap children.”
She said his actions “show a deep level of dysfunction, depravity and disrespect for and disregard of the rights of others and the community.”
The judge said, “Most importantly, the court has considered and respects the victims’ position in this case. And based thereon, the court agrees that your crimes warrant a consecutive sentence. Out of respect for the victims, the court bound itself to that agreement.”
With regard to the plea agreement, which avoids a trial requiring the victims to testify, Hawaii County Prosecutor Kelden Waltjen said in a written statement: “Our Office values victim input and the importance of victim well-being.
“Sexual assault cases, especially those involving minors, are some of the most traumatic types of criminal victimization. The victims and their families were consulted and very involved throughout the plea negotiations in this case.”
Waltjen lauded good Samaritans Bridge Hartman and Kori Takaki, “whose quick thinking and actions likely saved (the girl’s) life.”
He recognized the “bravery and courage” of both victims in the case.
“I hope today’s sentencing offers them and their families some closure and a sense that justice was served.
“Hawaii island is a big island but a small community,” adding, “We lean on each other for strength, and that’s what makes us resilient.”
He praised the hard work of Deputy Prosecutors Kate Perazich and Jackson, his office’s Victim’s Assistance Unit, the Hawaii Police Department, lead detective Steven Grace and the other officers and personnel who worked on the case, along with federal and state law enforcement partners.
Waltjen thanked the Missing Child Center and the Maile Amber Alert coordinator.
