The Hawaii doctor charged with trying to kill his wife during a birthday hike testified at his attempted murder trial Wednesday that he struck her in the head with a rock after she tried to shove him from a cliff.

Gerhardt Konig told the Oahu courtroom that Arielle Konig tried to push him from a trail near Honolulu on March 24, 2025 — her birthday — after they had an argument about an emotional affair she’d had with a co-worker.

His account differed sharply from Arielle Konig’s testimony about the alleged attack last week.

They scuffled after the attempted shove, and his wife grabbed him by the testicles and hit him in the head with a rock, Gerhardt Konig said. He said he eventually wrestled the rock away and hit her with it twice.

She scooted toward two hikers on the trail, Konig said, and told them he was trying to kill her.

In a daze, Konig said, he continued up the trail and called his son on FaceTime. During the conversation, he said, he told him that he planned to take his own life.

In sometimes emotional testimony, Konig, 47, an anesthesiologist, said he felt horrible that he’d hurt his wife. But he said he’d acted in self-defense.

Konig denied having planned the trip from their home in Maui to kill his wife and said he’d been trying to do something nice for her birthday.

Prosecutors charged him with second-degree attempted murder and accused him of pushing Arielle Konig toward a cliff on the Pali Puka Trail before he attacked her with a syringe and a rock.

In his testimony Wednesday, Gerhardt Konig denied having had a syringe with him. And he denied telling his son during the video call that he’d tried to kill Arielle Konig. Emile Konig, 19, testified Tuesday that his father had said as much.

Gerhardt Konig acknowledged the word “kill” might have come up in the conversation but said it wasn’t a confession.

“I think I was saying to myself, like, ‘she said I tried to kill her,’” he said.

Arielle Konig recounted the events for the jury last week, alleging that her husband attacked her after he asked her to pose for a cliffside selfie.

Feeling uneasy about the location, Arielle Konig said, she tried to move past him, but he grabbed her and pushed her toward the cliff. After she threw herself to the ground, she said, he came at her with a syringe and began bashing her head with a rock when she batted the device out of his hand.

“Nobody’s coming to save you,” she recalled him saying at one point.

She escaped, she said, and was helped by bystanders on the trail who called authorities. In a 911 call played in court, the hikers described seeing a man trying to kill a woman whose face was covered in blood.

Gerhardt Konig took the stand again Thursday and was cross-examined by Honolulu County Deputy Prosecuting Attorney Joel Garner. At one point, as the prosecutor grilled the defendant about his account of the hike, he showed the jury a pair of side-by-side photos from the incident’s aftermath.

In both, Arielle Konig’s face was covered in blood. Her husband’s face appeared to show minor bruising.

The alleged attack occurred three months after Gerhardt Konig discovered his wife had been having the emotional affair. They’d gone to counseling, Arielle Konig said, and appeared to be repairing the damage she’d caused to their relationship.

Gerhardt Konig said Wednesday that he was “devastated” by the affair, which he said she minimized and refused to answer questions about.