Lemrick Nelson is facing his third trial in connection with the stabbing to death of Yankel Rosenbaum, a 29-year-old rabbinical student, in 1991 during the Crown Heights riots in New York, one of the most vicious episodes of inter-racial violence between blacks and Jews.

Mr Nelson was acquitted of a charge of murder in 1992 at a criminal trial.

In 1997 he was convicted in a federal court of violating Rosenbaum's civil rights, on the grounds that the attack was anti-semitic. The verdict was overturned on appeal because the trial judge had improperly attempted to balance the number of Jews and blacks on the jury.

In both trials Mr Nelson denied killing Rosenbaum, saying evidence had been planted on him, and others had been responsible. The civil retrial began on Monday with a dramatic turnaround.

Mr Nelson admitted stabbing Rosenbaum, but said he had done so because he was drunk, not because his victim was Jewish. Since Mr Nelson has been acquitted of murder, and cannot again be tried for that crime, the issue is no longer that he attacked Rosenbaum, but why he did.

"Something happened that night. I stabbed somebody, but not because he was a Jew. I was drunk. I was high and I got caught up in the excitement," Mr Nelson said in his statement.

Rosenbaum's family reply that, far from clearing Mr Nelson, who was 16 at the time, of being motivated by anti-semitism, his admission further incriminated him. "The excitement was when that mob called out, 'There's a Jew, let's get the Jew,'" said Rosenbaum's older brother Norman. "It was the excitement of getting the Jew."

The conviction in 1997 was thrown out after the judge was accused of "jurymandering" in his attempts to balance its composition by race or religion, and jury selection in the current trial has been fraught.

A Jewish Puerto-Rican woman was excluded when it was pointed out that her son, like Rosenbaum, was a rabbinical student and that could influence her.

The case hinges on the atmosphere of mob violence and recrimination that dominated the night of August 19 1991 in Crown Heights, an area largely segregated between African-Americans and Caribbeans on one hand, and Jews on the other. A Hasidic man in a car ran over a African-American boy, Gavin Cato, seven, and was attacked by a black mob.

A Hasidic ambulance arrived and took care of the driver and left (under orders from the police, it later transpired) while the boy and his injured cousin had to wait for a city ambulance. He died, and hours later Rosenbaum was attacked as black youths started to riot. One man, Charles Price, was later convicted of instigating the attacks by calling on the crowd to "Get the Jew"and "An eye for an eye!"

A fear persists that the trial could reignite tensions in Crown Heights. Much has been done to repair community relations since the riots, but the calm is fragile.

"It's always a situation that could potentially explode," said one black activist who did not wish to be named. "Although it's been quiet for quite some time, and there have been reasonably successful efforts to reduce tension on both sides, the tensions are still there."

"We've learned to tolerate each other," said Isaac Abraham, a spokesman for the Hasidic community and the Rosenbaum family.

"The city of New York, all ethnic groups, don't need this trial," he said. "This Lemrick Nelson has nine lives."