Capitol Police say that the commander of officers on the House side of the Capitol left his service weapon unattended in a bathroom where it was discovered by another officer.

A spokeswoman for the department told Roll Call that Lt. Mike Byrd will be investigated after his Glock-22, which has no manual safety to prevent unintended firing, was found “during a routine security sweep” by another officer in a bathroom on Monday.

{mosads}“The Department takes these matters very seriously, and has a very thorough process to investigate and review incidents such as these, and holds personnel accountable for their actions,” spokeswoman Eva Malecki told The Hill. “Following the investigation’s conclusion, appropriate actions will be taken in accordance with the Department’s official policies and procedures.”

Monday’s incident appears to be the first unattended service weapon involving Capitol Police reported since 2015, when the department faced a rash of similar incidents including on where an officer’s loaded weapon was found on a toilet seat cover holder.

In another case that same year, a young child found an unattended gun in the bathroom of then-Speaker John Boehner’s (R-Ohio) office. That incident too involved a weapon without a traditional safety mechanism preventing unintended firing.

“Each disciplinary matter is thoroughly investigated and reviewed, employees are held accountable for their conduct, and they are provided due process in adjudicating these matters,” Capitol Police said at the time.

“Depending on the nature and seriousness of the violation, an employee’s record, and other ‎required considerations, an appropriate penalty is applied, up to and including termination of employment. As a matter of policy, the Department does not routinely discuss internal personnel matters, in order to maintain the integrity of the Department.”

-Updated 7 p.m.