PORTLAND, Maine — If history is any guide, Maine’s attorney general will declare the fatal shootings of three Mainers in the past two weeks by law enforcement officers as legally justified.

In the past two weeks police have shot dead three people in two separate cases, and four officers have been taken off active duty. The victims were Kadhar Bailey, 25, of Gardiner, Ambroshia Fagre, 18, of Oakland and Chance David Baker, 22, of Portland.

The Maine Office of the Attorney General investigates every time Maine police use deadly force to determine whether officers were legally justified in taking a life. The findings are made public.

In its more than 100 reviews of police use of deadly force since 1990, the attorney general’s office has never found that an officer should face criminal charges, according to department spokesman Tim Feeley, and a review of past cases.

The central test in the attorney general’s review is whether — in the heat of the moment — the police officer thought the person she or he shot was otherwise going to kill or hurt the officer or someone else. The review hangs in part on the standard of reasonableness — a legal test pervasive in the American justice system that is based on what investigators believe a reasonable person would do.

Here is how the attorney general’s office typically explains the two-step test:

First, the officer must actually and reasonably believe that unlawful deadly force is being used or is imminently threatened against the officer or others. Second, the officer must actually and reasonably believe that the officer’s use of deadly force is necessary to meet or counter that use or imminent threat of unlawful deadly force.

The investigation does not look at whether the use of deadly force could have been avoided.

In the Vassalboro case, three police officers — Lt. Scott Ireland and Trooper Jeff Parks of the Maine State Police and Vassalboro police Chief Mark Brown — were placed on administrative leave with pay, according to the Public Department of Public Safety. All three discharged their weapons, according to the attorney general’s office, but it is unclear who fired the fatal shots.

In Portland, following his shooting of Baker over the weekend, police Sgt. Nicholas Goodman was put on leave and faces an investigation by the attorney general’s office for a second time in his 14-year-career.

In 2008 Goodman, a decorated police veteran who teaches at the Maine Criminal Justice Academy, shot dead the driver of a Ford Explorer after the car dragged him nearly 300 feet. The attorney general found that Goodman was legally justified in shooting Albert Kittrell.

One of the first tasks of the attorney general’s investigators will be to determine exactly what happened in each of this month’s shootings.

In Vassalboro, officers shot Bailey and Fagre, who were suspected in a series of burglaries, after the pair intentionally rammed their pickup truck into a police cruiser, according to the Department of Public Safety.

In Portland, before Goodman fired the shot, Baker had been brandishing what appeared to be a rifle, but was later found to be a pellet gun, according to police. Goodman and the other responding officers had received conflicting reports that Baker was armed with a shotgun, rifle, or BB gun, a police spokesman said.

The Portland Police Department also will be conducting its own investigations, following the attorney general’s report. After police shoot someone, the department’s policy is to investigate as potential crimes the officer’s role, as well as what the victim did before she or he was shot.

The department also launches an internal affairs investigation to determine if the shooting violated any police policies. That probe is conducted by a group including a member of the public who has not served in law enforcement, a member of the Maine State Police, the chief of another police force, and various members of the local department.

That investigation covers the same ground as the attorney general’s, but also goes further by asking whether the department should make any policy or training changes and if the officer involved should face disciplinary action. Those decisions are left to the police chief.

Although the findings of internal affairs reviews are public records, according to Portland police policy, they are kept largely confidential and distributed only to a narrow group of police and city officials, including the mayor, city councilors and city manager.

The internal investigations also are reviewed by the Police Citizen Review Subcommittee. The citizen group is charged with determining whether investigations were “thorough, objective, fair and timely,” but does not have the power to overturn them or alter their outcomes.