BROOMFIELD, Colo. (KDVR) — Broomfield High School’s head football coach resigned from his position following a lengthy investigation into accusations of inappropriate behavior.

According to the Boulder Valley School District, Blair Hubbard submitted his resignation and it was accepted by the school on Monday.

In December, the Broomfield Police Department conducted an investigation into Hubbard amid the accusations. Detectives found Hubbard did not engage in any criminal behavior and no charges were filed. However, BVSD announced it would conduct its own administrative investigation.

In January, Hubbard was placed on paid administrative leave by the school pending the outcome of the ongoing investigation. At the time, the school did not release further information on what the investigation entailed.

In a statement sent to FOX31 on Tuesday, the police investigation was in regard to “accusations of inappropriate behavior involving several Broomfield High School students,” according to a report from the Broomfield Police Department.

According to BVSD, the investigation included interviews with 53 witnesses.

The report from the BVSD investigation was shared with Hubbard last week, and he submitted his resignation on Monday.

A letter from Principal Ginger Ramsey was sent to parents and students about the head football coach position. The letter confirmed that Hubbard would not return to his coaching and teaching positions at the school.

“We will work to hire a new head football coach at Broomfield High School as soon as possible and will be seeking student and family input in the hiring process,” said Ramsey in a letter to students and parents.

According to the Broomfield Eagles Football website, Hubbard has been the head coach at the school since 2016, and was described as “one of the most successful and winningest coaches in the state of Colorado.”