While he is charged with second-degree murder for shooting another man in 1991, Henneman's defense attorney argued that he committed manslaughter in recklessly causing the death of David Gibbins.

A jury of six men and six women reported Tuesday after two days of deliberations that it was hopelessly deadlocked on whether Henneman was guilty of second-degree murder or a lesser felony offense.

Henneman, 57, has been on trial in connection with the Aug. 18, 1991, shooting death of Gibbins, while the two were with a group on a four-day fishing and camping trip at Nuu Landing.

After the jury reported its situation, Judge Joseph Cardoza accepted the firearms verdict and declared a mistrial on the murder charge, setting a new trial date of Sept. 4. Cardoza ordered an updated presentencing report on Henneman but held off scheduling sentencing until the murder charge is resolved.

Gibbins' sister, who came to Maui for the trial, expressed disappointment at the lack of a full verdict, saying her family remains convinced Henneman is guilty of murder.

"We know it was murder so we are hanging in there to get the conviction," said Charlotte Rowland of Bentonville, Ark.

Jurors had been given options to find Henneman guilty of second-degree murder, manslaughter due to extreme or mental disturbance, or reckless manslaughter.

On the latter counts of manslaughter, Henneman would face up to 10 years in prison while murder carries a maximum mandatory sentence of life with the possibility of parole. The firearms charge also carries a maximum 10-year prison term.

Henneman, who remains in custody, was serving a term of life in prison with the possibility of parole after pleading no contest to second-degree murder. He was allowed to withdraw his plea in 2004, after he had been incarcerated for nearly 13 years. A judge ruled that Henneman's attorney at the time had given him wrong advice about the sentence he faced when he entered the no-contest plea.

Henneman readily acknowledged in trial testimony last week that he shot Gibbins after the two had been involved in both verbal and physical altercations. At one point, Henneman said Gibbins knocked him to the ground, kicked him and punched him, apparently believing that the defendant had improperly disciplined Gibbins' 12-year-old daughter.

"He picked me up, he grabbed me, flipped me over, slammed me down on the deck," Henneman told jurors in his defense.

Henneman said he reacted by going for an AR-15 assault rifle he had brought with him and loading it to confront Gibbins. He eventually fired the shot that struck Gibbins, a 40-year-old Makawao resident and father of two. Hit once in his middle-upper chest, Gibbins was dead by the time medical help arrived at the remote beach site between Kahikinui and Kaupo.

Deputy Prosecuting Attorney Melinda Mendes said she was disappointed by Tuesday's verdict, "but I have to respect the process."

She said her office planned to go forward with a second trial on the murder charge.

Henneman's attorney, Keith Shigetomi, whose practice is based on Oahu, listened in on Tuesday's verdict through a telephone conference call. Shigetomi suggested in closing arguments last Thursday that his client had acted recklessly, but was not guilty of murder.

Shigetomi acknowledged that Henneman had disregarded the risk of what he was doing and shouldn't have done what he did. He argued for a verdict of reckless manslaughter.

Rowland, Gibbins' older sister, had come to Maui with her daughter, Connie, for the trial.

"It (trial) made him come alive again and now he's gone again," Charlotte Rowland said in expressing her disappointment at the jury's verdict.

She said she knew her brother had housed Henneman at one point during their friendship, and she did not believe any of the defendant's testimony during the trial.

Her brother was a hardworking father, "a really good guy" who was portrayed unfairly by Henneman during the trial, she said.

"I'd like people to know his whole career was about saving people," Rowland said. "David wasn't perfect at all. But he didn't deserve to be shot at."

Connie Rowland said the trial has been a painful reminder of the family's loss of a loved one.

"We're grieving all over again," she said.