By Michelle McCaskill, Army Office of Special Trial Counsel

FORT LEONARD WOOD, Mo. – Two Army drill sergeants who engaged in prohibited sexual relationships with their trainees and conspired to cover it up have been sentenced to prison, ending their military careers.

Staff Sgt. Michael L. Serrano, 34, and Sgt. 1st Class Brian L. Sullivan, 39, both assigned to A Company, 2nd Battalion, 10th Infantry Regiment, 3rd Chemical Brigade, both pleaded guilty to their crimes during their court-martials April 21 – 22 at the Fort Leonard Wood courtroom.

On August 7, 2024, the day prior to her graduation from Basic Combat Training, the trainee victimized by Sullivan came forward with a letter to the unit staff duty officer describing how Sullivan pursued her which led to an intimate relationship. She also described how Serrano engaged in a similar relationship with another trainee.

The letter was shared with command leadership who provided the information to the Department of the Army Criminal Investigation Division and an investigation was initiated.

Army CID agents interviewed the trainees along with other witnesses who observed the actions and behavior of both Drill Sergeants towards the victims.

When interviewed by Army CID agents, Sullivan and Serrano conspired to cover-up their crimes by agreeing on a fabricated story in which they denied having any relationship with the trainees. The eyewitness accounts of several witnesses in the unit and the testimony of the victim trainees countered these false claims.

Serrano pleaded guilty to wrongfully attempting to develop a sexual relationship with a trainee and engaging in prohibited sexual activity with a trainee. The military judge sentenced him to 47 days in prison, a reprimand, reduction in rank to E-1, and he will receive a General Discharge from the Army through a subsequent command initiated administrative action.

Sullivan pleaded guilty to abusive sexual contact and was sentenced by the military judge to 84 days in prison, reduction of rank to E-1, and he will receive an Other Than Honorable discharge from the Army through a subsequent command initiated administrative action. Upon release from prison, Sullivan will be required to register as a sex offender and will be subject to federal and state sex offender registration requirements.

Per the terms of their plea agreements, the government dismissed the remaining charges for both defendants.

“The conviction and sentence in this case shows the seriousness in which the Army takes these types of offenses and the commitment to providing a safe and secure environment in which trainees take their first steps forward as members of our force,” said Capt. Tyler Eason, prosecutor, Fourth Circuit, Army Office of Special Trial Counsel. “Through the investigative work of Army CID and the courage of the victims in this matter, these Drill Sergeants were held responsible for their actions.”

Serrano and Sullivan will serve their prison sentences at the Midwest Joint Regional Correctional Facility at Fort Leavenworth, Kan.

This case was investigated by Army CID’s Fort Leonard Wood Resident Agency and prosecuted by Eason and Capt. Alex Egan, 3rd Chemical Brigade.

The Army Office of Special Trial Counsel is comprised of specially trained military lawyers, legal professionals and support staff responsible for the expert and independent prosecution of murder, sexual assault, domestic violence, child abuse, kidnapping and other serious criminal offenses. Headquartered at Fort Belvoir, Va., OSTC has eight regional headquarters that oversee 28 field offices located across the country to include Europe and Korea. For more information visit https://www.army.mil/ostc.

If you would like to report a crime, have information about a crime, or have been the subject or survivor of a crime, you can submit anonymous tips to Army CID.