A portion of the Berlin Wall

BERLIN (CNN) -- The trial of a former East German refugee who shot a border guard while escaping to the West in 1962 during the Cold War, begins Monday in this now-united city.

Rudolf Mueller, 67, was a young baker when he fled with his family by tunneling under the then-new Berlin Wall.

While hundreds of former East German border guards and officials have been prosecuted since German unification in 1990, on charges relating to shootings of East Germans trying to flee to the West, Mueller's is believed to be the first case involving prosecution of a refugee.

The trial comes amid claims in eastern Germany of "victor's justice" or failure to prosecute cases such as Mueller's.

Justice Ministry spokesman Matthias Rebentisch denied prosecutors had dragged their feet in bringing charges against Mueller, blaming the heavy workload borne by the agency responsible for sorting through the massive numbers of secret files kept by East Germany's security apparatus.

"Whatever is there to be pursued, prosecutors have to pursue it and they do so, no matter which political side the perpetrator and victim were on," Rebentisch said. "It's solely about clearing up crimes."

Mueller, who was held briefly after being charged in June 1997, then released on 100,000 marks ($60,000) bail, has declined to comment before the trial.

In 1962, before the Wall was built, he spent weeks digging a 22-meter (72-foot) escape tunnel. On June 18, 1962, while leading his family to a building near the tunnel, he was stopped by a guard, 20-year-old Reinhold Huhn, who was armed with a machine gun.

The guard asked to see the family's papers, Mueller later told West Berlin police. He said that as Huhn examined a bag, Mueller punched him, knocking him down. Another border guard opened fire, hitting the guard, Mueller claimed, adding that the family then fled to the West.

But prosecutors say Mueller shot Huhn point-blank before the guard had time to react. They cite Mueller's own remarks during a post-escape news conference at one of West Germany's biggest publishing houses, Axel Springer, which had allowed him to dig the tunnel from its basement.

When Mueller was asked how many times he had to "pull the trigger" while escaping, he was quoting as replying: "Once. The man fell down immediately."

Although East Germany demanded that Mueller be handed over after the shooting, West Germany refused.

Eventually, Mueller became a union official and businessman.

In East Berlin, near the Checkpoint Charlie border crossing, a street was named after Huhn, who had helped build the Berlin Wall during his military service.

Mueller's trial is scheduled to last until February 26.

The Associated Press contributed to this report.