URUMA, Okinawa — A Marine officer remained in Okinawan police custody Monday, suspected of driving under the influence of alcohol and possessing an illegal knife.

An Okinawa police spokesman said a 24-year-old first lieutenant was arrested July 15 for possessing a knife with a blade measuring 8.2 centimeters (about 3.23 inches), just over the 8-centimeter (3.15 inches) legal limit.

His name is being withheld until formal charges are filed.

The lieutenant was arrested in a convenience store parking lot in the Maeganeku district of Onna at 3:40 a.m., said the spokesman for the Okinawa Prefectural Police station in Uruma. The arrest was made by road patrol police officers who had set up a vehicle checkpoint in the neighborhood.

Police would not say why the lieutenant was searched, but local press accounts stated he had been observed swerving into the parking lot to avoid the traffic checkpoint.

The police spokesman confirmed the officer was given a Breathalyzer test at the scene and it detected an alcohol level above the legal limit of 0.15 milligrams per liter.

A charge of violating Japan’s swords and firearms control law was forwarded to the Naha District Prosecutor’s Office on July 17, the police spokesman said.

No information concerning the suspect was available Monday from Marine Corps Public Affairs.

“We can confirm that a servicemember is being held on allegations of driving under the influence and violating Japan’s swords law, but that’s all we can release until charges are actually filed,” said 1st Lt. Clint Gebke Monday afternoon.