EPHRATA - The State Patrol is continuing its investigation into a missing M16 rifle from the Grant County Sheriff's Office.

Robert Calkins, of the State Patrol, said Thursday the rifle was discovered missing late last year and the sheriff's office completed a diligent inventory investigation, including searching deputy patrol cars as well as reviewing deputies' personal and department issued firearms.

The case was made public Thursday when Sheriff Tom Jones told area media.

The state patrol is now looking into the incident as a criminal investigation, Calkins said. The sheriff's office contacted the State Patrol in February to begin the investigation.

Calkins added no other information can be released at this time because the investigation is ongoing.

The missing rifle is an M16, .223-caliber, fully automatic rifle issued to patrol deputies.

Sheriff Jones added many citizens have come forward with offers to help find the missing weapon.

Anyone with information is asked to contact the sheriff's office at 509-754-2011, ext. 468 or send a tip to crimetips@co.grant.wa.us.ll. Tipsters can remain anonymous.

"I am enormously concerned about this missing rifle," Jones said. "I am sorry to alarm the public that such a weapon has been lost from our control, and I reassure everyone that we will find the rifle and anybody who is found to be responsible for any malfeasance will be held accountable at the highest level."

Jones said the rifle was unaccounted for during a sheriff's office audit and equipment inventory, which is done on a regular basis. The rifle was reportedly kept in a secured firearms room at the Grant County Courthouse in Ephrata.

Immediately after the rifle was discovered missing, the sheriff's office conducted an internal audit and investigation, but have not located the weapon. Jones has asked the state patrol to begin their own investigation to provide "a set of eyes from outside investigators."