No charges were brought despite the fact that after the passage of the War Crimes Act in 1991 Strathclyde Police set up a unit with, in effect, with the sole purpose of building a case against Mr Gecas.
He was on the first list of suspects brought to Britain in 1986 by the Simon Wiesenthal Centre, the group which has lead the search for former Nazi war criminals.
Last year the unit was disbanded after spending pounds 400,000, with no prosecution.
Three years ago Mr Gecas sued Scottish Television for pounds 600,000 over a documentary which alleged that he was involved in the wartime murder of Jews and civilians while serving with a police battalion. Mr Gecas lost the defamation case.
The judge in the case, Lord Milligan, said he was "clearly satisfied" - on the balance of probability, the standard of proof which applies in civil cases - that Gecas took part in many operations involving the killing of innocent Soviet citizens "and in doing so committed war crimes against Soviet citizens who included old men, women and children".
As a young man, Mr Gecas joined a Lithuanian police battalion as a lieutenant in charge of a platoon.
The police battalion killed thousands of Lithuanian Jews who had been rounded up from city ghettos, towns and villages.
By the autumn of 1941, when there were few Jews left in Lithuania, the battalion and others were taken by the Germans to do a similar job in German-occupied Belorussia (now Belarus).
By 1944, the battalion was being used to help prevent the Allied advance in Italy and, in September, Mr Gecas's company was captured by the US army. He changed sides and fought for a Polish regiment.
He was able to launder his past and came to Britain as a Pole.
By 1956, he was a British citizen. He married a 19-year-old nurse in 1959, when he was 43 and worked for the National Coal Board until his retirement in 1981.
Mr Gecas has publicly admitted that he joined the battalion, went with the Germans to Belorussia, and later wore German uniform and fought in Italy.
However, he has said that if Jews were rounded up and killed, he had no knowledge of it.
Mr Gecas has avoided making any public comment since the libel action.Reuse content