Three students were expelled from Liberty High School after they were found with marijuana.

School administrators are conducting an on-going drug investigation at the school, said King County Sheriff’s Office spokesperson Sgt. John Urquhart.

None of the students was booked by the King County Sheriff’s Office, and charges won’t be filed until the “green vegetable matter” is analyzed by a lab, he said.

The first incident was Jan. 13, when a school resource officer discovered a 15-year-old student had marijuana, he said.

During the week that followed, staff found drugs on two more students, ages 17 and 18.

The Sheriff’s Office hasn’t revealed how the drugs were found to avoid compromising further “discoveries,” Urquhart said.

The Sheriff’s Office is not conducting an ongoing investigation at the school, but it will take action when drugs are found or suspected, he said.

In each case, the amount of marijuana found was very small.

The expulsions were considered “emergency,” meaning administrators may change the penalty, said Issaquah School District spokesperson Sara Niegowski.

Administrators removed the three students for safety reasons, she said. “At the end of the investigation, they determine what the ultimate discipline is,” she said.