A Hawaii jury heard testimony that a son watched his father appear on FaceTime with blood on his shirt and admit he had just tried to kill his wife before saying he planned to jump off a cliff ahead of police.

Prosecutors are relying heavily on that account from Emile Konig as they build their case against Gerhardt Konig, a doctor who is accused of attacking his wife, Arielle Konig, near the Pali Puka Trail on Oahu in March 2025.

Emile, who was living with the couple and his younger siblings in Kahului, Maui, said the call came shortly after the alleged attack.

“He would not be making it back to Maui and to take care of the younger kids and that Ari, my stepmom, had been cheating on him and that he tried to kill her,” Emile testified, recounting what his father told him, according to Hawaii News Now and courtroom testimony.

Gerhardt Konig appears in a Hawaii courtroom
Hawaii doctor Gerhardt Konig appears before a judge via video during an arraignment hearing after being indicted on allegations of attempting to kill his wife on Monday, April 7, 2025, in Honolulu. (AP Photo/Marco Garcia)

Jurors heard the first call came at 10:42 a.m., when Konig allegedly told his son he was not coming home and needed him to step in for the family. He also claimed Arielle had been unfaithful and said he had just tried to kill her.

About an hour later, Emile testified, his father called again on FaceTime, where he appeared with blood on his shirt.

Emile told the court he saw blood on his father’s shirt.

During the call, Konig again spoke about the alleged affair and the attack, and then described what he planned to do next.

“During that call, the next plan that he said was to jump off the cliff,” Emile testified. “I told him not to.”

Prosecutors say Konig ended the call with a stark warning: “I’m going to go before the police catch me.”

Emile also testified his father never claimed self-defense during either call, a key point as the defense has argued Arielle was the initial aggressor.

During cross-examination, defense attorney Thomas Otake pressed Emile on specifics of the FaceTime call.

Emile confirmed he saw blood on his father’s shirt and that Konig said it belonged to Arielle. He also testified that his father told him the blood came from her head and that Arielle had been cheating on him for “a couple months.”

Otake also asked whether everything had seemed normal earlier that morning.

In the courtroom, Konig reportedly showed no visible emotion as his son testified. Emile’s grandparents also watched quietly from the gallery, Hawaii News Now reported.

Earlier in the trial, Honolulu Police Department digital forensics examiner Det. Thomas Iinuma detailed what prosecutors describe as a troubling digital trail in the months leading up to the incident.

Hawaii doctor Gerhardt Konig appears before a judge via video during an arraignment hearing after being indicted on allegations of attempting to kill his wife, April 7, 2025, in Honolulu. (AP Photo/Marco Garcia)

Investigators recovered data from Konig’s laptop, where a single active user profile, “GKonig,” contained a series of late-night Reddit searches and posts focused on infidelity, betrayal and divorce.

On Dec. 24 and 25, 2024, Konig allegedly browsed threads with titles such as “Lying again,” “It’s over,” and “I did a horrible thing,” many within forums dedicated to coping with infidelity.

One post read: “My wife cheated on me two years ago and I forgave her… How can I trust her again?”

Authorities also found that Konig purchased a voice-activated audio recorder and later searched for remote Maui hiking locations, including detailed information about the Pali Puka Trail, which is known for steep, dangerous cliffs.

Keyword analysis of the device revealed repeated searches including “danger,” “death,” “fall,” “kill,” “die,” “cliff,” and “hike.”

A Dropbox folder labeled “Divorce” was also discovered.

Gerhardt Konig is charged with attempted second-degree murder after he allegedly tried to kill his wife while hiking in Hawaii.  (Gerhardt Konig/Facebook)

Family members also testified that the relationship between Gerhardt and Arielle Konig had grown increasingly tense.

Peter Mast, Arielle’s stepfather, said the marriage had cooled over the past year, though Konig appeared to act as if “everything was normal” at a family gathering in January.

Arielle’s mother, Judith Mast, described tension and emotional distance but said the relationship appeared to be improving before the incident.

After the state rested its case, prosecutors pointed to Emile Konig’s testimony as a critical piece of evidence supporting their narrative of what happened.

They said his account provides a direct window into the defendant’s mindset immediately after the alleged attack, linking the digital evidence, the alleged motive of infidelity, and the events on the cliff.

The defense is expected to continue arguing that the incident stemmed from a confrontation initiated by Arielle.