Court records reveal Līhuʻe manʻs alleged threatening letter to Kauaʻi council member ahead of court appearance

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A Līhu‘e man accused of leaving a “threatening note” on the desk of a Kaua‘i County Councilman is scheduled in District Court on Tuesday for a status review hearing, while the county prosecutor confirmed the office has transferred the case to Honolulu due to a conflict of interest.

Facing first-degree terroristic threatening, a class C felony, and harassment, a petty misdemeanor, 67-year-old Glenn Gruenhagen is in jail on $100,000 bail for reportedly leaving the “threatening note” for County Councilman Bill DeCosta in January and returning days later to look for him at the county building.

Despite DeCosta stating that the letter was a death threat earlier this month, upon obtaining the piece, the document instead appears to accuse DeCosta himself of decades-long harassment.

The letter was left for DeCosta at the Historic County Building in Līhu‘e on Jan. 12 and reported to police on Jan. 16. Through the course of their investigation, the letter — also described as a poster — was attributed to Gruenhagen, a local artist on the island.

Lihuʻe man Glenn Gruenhagen was arrested after this document, described as a threatening letter by the Kauaʻi Police Department, was left on council member Bill DeCostaʻs desk on Jan. 12. (Photo obtained from court records)

The letter reads: “Old Dogs Rule. Councilman ‘Billy De Goat’ hunted me down, like a wild animal, in Kokeʻe for 25 years and couldn’t catch me! Cuz, I own a dog! Run your dog, not your mouth! Billy hunted becomes hunter it’s election year! Once you’ve hunted humans there’s no other game! Let em know who’s boss! Old Dogs Rule.” 

The words aimed at DeCosta are written in thick black ink horizontally on blank paper with elements of the US flag drawn across the top and alternating thick stripes of yellow, blue, and red painted over the text.


In a declaration to the judge, DeCosta wrote that he didn’t know Gruenhagen, but his memory of an encounter with him was jogged after seeing security footage. 

DeCosta described meeting Gruenhagen while working as a teacher on a school field trip between 2014 and 2018. During the field trip, DeCosta brought students to Kōkeʻe Lodge to “participate in the native plant hike and some organized games on the meadow.” He then encountered Gruenhagen with his dog and remembered asking Gruenhagen to put his dog on a leash, as the dog was running around and had bitten one of his students. 

“Mr. Gruenhagen became visibly upset, refused to put his dog on a leash, and continued to allow his dog to run around the meadow without a leash,” he said.

“The next morning, a dog pelt that resembled the pelt of Mr. Gruenhagen’s dog was found on one of the picnic tables in the meadow with flowers and a note by it.”

The note implied ‘You made me do this to my dog,’ DeCosta said.


DeCosta said that after Gruenhagen dropped off the document on Jan. 12, he returned two more times, on Jan. 17 and on Jan. 19.

“Office staff told me that Mr. Gruenhagen was pounding on the door looking for me,” said DeCosta, of the Jan. 17 event.

On Jan. 19, DeCosta said that Gruenhagen had talked with a colleague and/or security personnel and had accused DeCosta of “hunting him for 25 years,” saying, “the hunter has become the hunted”, and”once you hunt human the game has changed.” DeCosta also reported that one of his unnamed colleagues witnessed Gruenhagen “take out a knife from his backpack to cut some plastic off of a lock and put the knife back into his backpack.”

Gruenhagen was later arrested and has been at the Kauaʻi Community Correctional Center since Jan. 25. He pleaded not guilty to the charges.

Fifth Circuit Court Judge Kathleen Watanabe granted a suspension in court proceedings on Feb. 6 for Gruenhagen to undergo mental fitness and capacity evaluations.


Since then, the Kaua‘i County Prosecuting Attorney’s Office has conflicted out of the case “The case is being handled by the Honolulu Prosecutorʻs Office due to Mr. DeCostaʻs role as a council member,” stated Johnette Chun, executive assistant with the County of Kauaʻi Office of the Prosecuting Attorney, in an email.

Glenn Gruenhagen (Courtesy of the Kauaʻi Police Department)

Council Chair Mel Rapozo said he had “no information” on the conflict case and referred all questions to the prosecutorʻs office.

Rapozoʻs wife, Patsy Rapozo, serves as the Circuit Court Clerk at the Kauaʻi Fifth Courthouse. However, any potential perceived conflict of interest with DeCosta was not the cause of the transfer. “This has nothing to do with Patsy,” Chun replied.  

Kaua‘i Now requested to interview Gruenhagen while in jail, but the request was denied by the Hawai‘i Department of Corrections and Rehabilitation.

“He cannot be interviewed at this time because of the ongoing case proceedings,” said Public Information Officer Rosemarie Bernardo.

The incident occurred roughly around the same time that DeCosta was placed on administrative leave from his teaching position at Kapaʻa High School in January due to an undisclosed incident.

However, the Department of Education has confirmed that the school investigation is not connected to Gruenhagen.

“Mr. DeCosta currently remains on Department Directed Leave during the ongoing investigation and is still employed by the Department,” said Department of Education Communications Specialist Derek Onishita.

“I’m not referring to that individual (Gruenhagen),” Onishita said in a follow-up email response.

Onishita declined to provide any details related to the ongoing investigation at the school, saying that the investigationʻs integrity and employee privacy rights needed to be protected.

Emma Grunwald
Emma Grunwald is a reporter for Kauaʻi Now. You can reach her at
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