A State Police trooper on military leave for the past five years was arrested last night on charges he drove home drunk and then pointed a loaded gun at an off-duty Boston officer who tried to get him out of his car to await arrest.

The incident occurred last night on South Munroe Terrace, where Timothy Walsh lives.

Walsh, 41, had served 18 years as a trooper before going on military service. According to a statement from State Police, Walsh had been on leave from the military for the past five years.

"The weapon allegedly brandished by the trooper was not his Department-issued weapon," State Police said in the statement. "That service-issued gun was turned in to the Department when the trooper was granted military leave approximately five years ago."

State Police will hold a hearing this week to determine whether Walsh should be kicked off the force. The Suffolk County District Attorney's office says Walsh will be arraigned Monday in Dorchester District Court on charges of assault with a dangerous weapon, illegal discharge of a firearm, operating under the influence, and leaving scene of an accident causing property damage.