The former Mililani High School athletic director accused of stealing over $400,000 from the school’s nonprofit sports booster club pleaded not guilty Monday to theft charges.

Glenn S. Nitta, 75, was indicted March 3 and charged with three counts each of first- and second-degree theft, and two counts of failing to report income. He surrendered to state sheriff’s deputies March 6 and posted bail.

Nitta entered a plea of not guilty Monday before Honolulu Circuit Judge Christine E. Kuriyama. His trial is scheduled for May 15 before Judge Catherine H. Remigio.

First-degree theft is a Class B felony punishable by up to 10 years in prison and a $25,000 fine, while second-­degree theft is a Class C felony punishable by up to five years in prison and a $10,000 fine. If Nitta is convicted of multiple charges in the case, the law allows a judge to impose an extended prison term.

Nitta remains free before trial on $500,000 secured by a bondsman. His attorney, Scott K. Collins, told the Honolulu Star-Advertiser after his client’s appearance he will review evidence in the case before taking their next step.

A 2021 investigation by two Mililani High School vice principals into allegations of theft from the Mililani High School Athletic Booster Club Inc. concluded that Nitta allegedly used the nonprofit’s money to pay $364,709 for personal expenses. Those expenses included gambling at the Tropicana in Las Vegas; business, car and student loans; four credit cards; and checks made out to family members with the last name Nitta.

The school’s more than 30 varsity and junior varsity sports teams have not recovered any of the money lost, which was raised from concession sales at games, car washes, Christmas gift wrappings and other fundraisers.

Honolulu police told the Honolulu Star-Advertiser that the investigation into the theft from the shuttered domestic nonprofit corporation “is continuing.”

“No further information is being released at this time,” said Michelle Yu, HPD spokesperson.

The Department of the Prosecuting Attorney declined comment.

School officials reviewed 65 bank statements and 1,235 cleared checks from the booster club from Sept. 1, 2015, to Jan. 1, 2021. Nitta served as president of the school’s now-­dissolved nonprofit.

He taught at Mililani for 48 years and also coached the junior varsity and varsity baseball teams before retiring on March 31, 2021, nine days after the school reported the theft to police.

The nonprofit was incorporated on Aug. 23, 2001, for the purpose of “fund­raising to support athletic programs at the school,” according to records kept by the Business Registration Division of the state Department of Commerce and Consumer Affairs.

The club’s listed officers were Nitta’s wife, Gaile Nitta, secretary; brother-in-law Phillip Carlos, director; sister-­in-law Helen Carlos, treasurer; daughter Glenelle Nitta, a director and a physical education teacher and softball coach at Mililani High School; and son Galenn Nitta, a director.

The Mililani High School Athletic Foundation is a new nonprofit organization and is not affiliated in any way with the closed corporation or its officers, according to school officials.