(AP) — Officials are maintaining the tighter security at Burwell schools more than a month after a menacing letter was sent to Burwell police containing what’s been called a “hit list.”

On the list received March 6 were the names of more than a dozen Burwell administrators, teachers and students at the district’s junior-senior high school. Nebraska State Patrol Lt. Dennis Leonard said there’s no new information on the case and that investigators are awaiting laboratory results.

After the school board met on March 10, Burwell’s two schools were closed for a day before reopening with new security procedures in place. Burwell Junior-Senior High School principal Dave Owen says students have adjusted well.

Burwell is a central Nebraska community of about 1,200 residents.