A former Montgomery County police officer, who eluded Washington area authorities for four years until his capture in West Virginia last May, went on trial in Montgomery Circuit Court yesterday on the first of several charges of armed robbery pending against him.

Joseph Ezekiel Baltimore, 40, who served as a Montgomery patrol officer in Bethesda for seven years, has pleaded innocent to the charge being tried. And his attorney argued yesterday that he fled only because of unfair treatment that caused him to lose faith in the justice system.

Baltimore was wanted by Montgomery, Prince George's and Fairfax police on four armed robbery charges when he disappeared in 1980.

In the Montgomery trial, Baltimore is accused of armed robbery and use of a handgun in the May 10, 1980 robbery of a now-closed Safeway store that was located on Nelson Road in Rockville.

Prosecutor Matt Campbell told the jurors the case is straight-forward, involving identification of Baltimore by the robbery victim.

Defense attorney Courtland Townsend Jr. said Baltimore was falsely accused and, having lost faith in the system of justice, fled, feeling "the need to hide out . . . until he could raise money to defend himself."

In 1977, while still a police officer, Baltimore was charged with raping a 15-year-old girl. A Montgomery Circuit Court jury acquitted him but he was later dismissed from the force after a police trial board hearing. That ruling was overturned by a Circuit Court judge.

In his opening arguments yesterday, Townsend said Baltimore nonetheless "was kicked off the police force" and hearings to clear his name were "never scheduled."

That treatment by the police force, coupled "with the animosity he felt against him," led Baltimore to conclude "the only safe thing he could do was get out. . . . " Townsend said Baltimore's brother was driving him back to Montgomery from a party in the District of Columbia the night of May 30, 1980 when they heard on the radio that police were searching for Baltimore following a robbery and shoot-out in Fairfax and a high-speed chase to Bethesda.

That information caused Baltimore to flee, Townsend said. He said witnesses cannot be located to provide an alibi for his client.

Testifying for the prosecution, Raymond William Walker, manager of the Safeway, said he identified Baltimore's photograph shortly after the robbery from an array of pictures presented to him by police. But Walker stopped short of identifying Baltimore in court yesterday, saying that the defendant "is heavier in the jowls plus he has a mustache that he didn't have then."

Baltimore is expected to take the stand in his own defense later this week.