Wednesday 10 a.m. — This story has been updated, click here for the latest on the investigation.

Tuesday — A long-time Trumbull police officer was arrested Monday for alleged sexual assault on a teen girl, who was part of Police Explorer program.

State Police arrested William Ruscoe, 44, Monday night, and charged him with second-degree sexual assault, third-degree sexual assault and fourth-degree sexual assault. He is also charged with tampering with a witness.

According to court documents, Ruscoe had befriended the teen, now 18, through the program. He allegedly sent her sexually explicit messages and photos for months. In one incident, after working together at an event at Trumbull High, Ruscoe allegedly drove her back to his Trumbull home. The victim told police that once Ruscoe convinced her to enter the house, he took his firearm out of its holster and put it on a counter, while looking at her in a threatening way. The teen told police he brought her upstairs and,  ignoring her protests,  sexually assaulted her.

Trumbull Police are not commenting on the investigation, since it is being handled by State Police, but Chief Thomas Kiely did say Tuesday that the charges are related to Ruscoe's off-duty conduct with a member of the department’s Explorer Program, of which Ruscoe is an advisor. Ruscoe has been suspended from duty and an internal investigation is underway to determine if he has violated any departmental policies, Police Chief Thomas Kiely said Tuesday in a statement.

“I am deeply troubled and concerned by the nature of the charges that have been presented,” Kiely said. “We will make every effort to ensure that the integrity of the department and its officers is preserved as this case is investigated and that the case is handled in a fair and timely manner.”

The Police Explorers program is described as offering direct experience in community police work for youth ages 14 through 21 interested in law enforcement.

The State Police Major Crime Squad of Troop C in Tolland handled the investigation. Ruscoe's attorney, Michael Fitzpatrick, said his client will appear in court March 5.

"We anticipate entering a plea of not guilty," Fitzpatrick told The Times.

Ruscoe joined the Trumbull Police Department in 1994 and has been an advisor with the explorer program for several years.