A state judge said he doesn’t believe the testimony of the first of two teenagers to stand trial in connection with the fatal beating of a taxi driver last year.

But Circuit Judge Dexter Del Rosario also said the state did not prove Michael Robles intended to kill or knew his actions would lead to death.

For that reason, Del Rosario found Robles guilty Thursday of manslaughter instead of murder as charged. He scheduled sentencing for September.

The possible penalties for manslaughter are either a 20-year prison term or 10 years’ probation.

However, defense lawyer William Jameson said he will ask Del Rosario to sentence Robles, who is 19, under state law intended for adult defendants under age 22, which would reduce the prison term to eight years.

The other teenager, 18-year-old Kilani Derego, is scheduled to stand trial in October. Robles will be required to testify.

Robles said he and Derego, his childhood friend from Hawaii island and fellow resident of a Hale Kipa group home in Manoa, entered a cab driven by Charlys Ty Tang in Waikiki just past midnight May 1 last year and went to Waipahu. Robles said he also smoked marijuana.

But when police arrested him six days later, he said he wasn’t in Waipahu.

"Mr. Robles’ statements on his role were self-serving and progressed from saying at first he was not present at the crime, minimizing his role in the event and blaming Mr. Derego, testifying among other things, that he actually struck Mr. Tang in order to protect him from Mr. Derego," Del Rosario said.

When they arrived in the Waipahu Times Super Market parking lot, Robles said, Derego and Tang got into an argument, and Derego started beating Tang. He admitted to kicking Tang, who was on the ground holding onto Derego’s leg, to break his friend free, then tried to pull Derego off Tang.

An ambulance took Tang in critical condition to the Queen’s Medical Center, where he died later that day, his 41st birthday.

Jameson had argued that the case should never have been charged as murder and that Robles was guilty at worst of misdemeanor assault for admittedly kicking Tang twice in the chest while Tang was on the ground.

"(Robles) can understand why the judge did not believe him, but he also feels that the judge applied the law correctly. He has no quarrel with the fact that he had a fair trial. And he’s happy with his decision to have gone jury-waived," Jameson said.

A jury, not a judge as in Robles’ trial, will decide the facts in Derego’s trial. And it could be a replay of Robles’ trial because Robles is expected to testify and is the only person to offer an account of what happened.

Police have not found any independent witnesses to the beating, and Derego is saying in court documents that he wasn’t there.

"Judge Del Rosario’s findings apply only as to defendant Robles, and a subsequent jury should not know (his) findings because they are irrelevant as to Mr. Derego’s trial," Deputy Prosecutor Scott Bell said.