An administrative error led to the hiring of dozens of Alameda County (California) sheriff’s deputies who had scored below acceptable levels on a pre-employment psychological exam, resulting in the department suspending them last week, CBS News reports.

On Friday, Sheriff Gregory Ahern sent letters to 47 deputies involved, explaining that when they took the test during their hiring process, they scored a “D” on a standard school grading A-through-F system.  While in a scholastic setting a “D” is a barely-passing grade, it fell below the standard the department put in place in 2016, Ahern explained.

The deputies will have the opportunity to take the test again to retain their positions, but in the meantime, they are barred from carrying a weapon or any credentials from the sheriff’s department, and they are banned from making arrests or enforcing laws in an official capacity.  A number of them will be retained to take administrative positions, allowing uniformed officers in those positions to take up patrol duties.

The sheriff’s department undertook a review of testing scores after one its deputies, Devin Williams Jr., was arrested earlier this month and charged with a double homicide.  Investigators found Williams’ employment test scores were below acceptable minimums, but he was hired anyway.  An expanded audit of tests scores found at least four dozen officers with unsatisfactory scores had been hired since 2016.