LONDON (AP) _ Prosecutors abandoned their war crimes case against an 86-year-old man today after a jury decided he was unfit to stand trial because he suffers from dementia.

Solicitor-General Sir Derek Spencer said the government would not proceed against Szymon Serafinowicz, who was accused of murdering three Jews during the German occupation of Belorussia, now Belarus, in 1941-42.

He had pleaded innocent to the charges, and a jury had been chosen to hear the case.

But in a rarely used procedure, the question of the defendant's fitness was put to the jury after eight days of arguments and expert testimony.

Serafinowicz's defense team argued he was suffering from dementia, probably Alzheimer's disease, and would be unable to comprehend the charges and testimony.

The prosecution called its own expert witness, who testified Serafinowicz was capable of standing trial.

Dr. Nicholas Stoy, Serafinowicz's physician from 1979 until last summer, testified he saw Serafinowicz in December at a hospital where the older man was being treated for pneumonia.

``He just looked blankly at me. I had to tell him my name,'' said Stoy, adding that the same thing happened again a few days later.

Stoy also testified that Serafinowicz's mental condition had deteriorated markedly between 1995 and 1996.

But Dr. Philip Joseph, a psychiatrist called by prosecutors, testified he believed Serafinowicz was only ``suffering the normal memory loss associated with aging'' and could stand trial.

When charges were filed against Serafinowicz last year, Efraim Zuroff of the Simon Wiesenthal center in Jerusalem said he was police commander in the Mir district of Belarus starting in 1941 and ``was actively involved in the persecution and murder of thousands of Jews.''

An estimated 200,000 Jews were killed in Belarus during World War II, when the country was part of the Soviet Union.

Serafinowicz, who took British citizenship after arriving in 1947, is the first person charged under Britain's 1991 War Crimes Act. The law permits prosecution of alleged war criminals who were not British residents at the time for crimes not committed on British soil.

Unlike the United States and some other countries, Britain refuses to extradite suspected war criminals.

Three charges had been filed against Serafinowicz.

The first accused him of murdering an unidentified Jew on Nov. 9, 1941, in Mir, Belorussia, a town then under German occupation, ``in circumstances constituting a violation of the laws and customs of war.''

The second alleged the murder of another unidentified Jew between Dec. 31, 1941, and March 1, 1942, in the village of Kryiczne. The third charge alleged he murdered another Jew between Jan. 1 and May 2, 1942, in Dolmatowszczyzna, another village under German occupation.