THE TRIAL OF IVAN THE TERRIBLE, by Tom Teicholz; St. Martin’s Press, 354 pages, $22.95.

Among Nazi concentration camps, Treblinka was uniquely horrific and hopeless — “the air was impregnated with death,” is how the place was described by one of the few Jews ever to leave it alive.

And the most frightening figure at Treblinka was “Ivan the Terrible,” a sadistic captive Ukrainian guard who operated the gas chamber and took fiendish delight in torturing and mutilating those who were about to die.

Tom Teicholz has written a valuable account of the controversial trial of deported American John Demjanjuk.

More than 870,000 men, women and children were murdered at Treblinka from August 1942 to September 1943. At Treblinka’s deadly peak, 15,000 people were being gassed there each day. Then the camp was dismantled and plowed over so its existence would never be known.

Remarkably, a few hundred Jews escaped on Aug. 2, 1943, during a brief uprising. Most were hunted down, but about 50 survived to tell the world about what they had seen.

Starting in 1977, several of those survivors positively identified Demjanjuk — a Cleveland auto- worker, naturalized citizen and classic “quiet neighbor” — as Ivan.

It was the eyewitness testimony of those forced to work near him at Treblinka that Demjanjuk couldn’t shake. Indeed, as this book makes clear, the real issue was not whether the Treblinka survivors could remember him after 45 years, but how could they ever forget him.

The image of Ivan was burned into their souls; they had him, even down to his characteristic walk: small steps, arms swinging — the way Demjanjuk walked.

“To the listener today — after a half century of Holocaust accounts — each survivor’s tale can sound remarkably similar,” Teicholz writes. “The horror becomes routine. Yet for each survior, his or her individual experiences were unlike another’s. Words fail to communicate the humiliations and degradations.”

Confusing media coverage of Demjanjuk’s prolonged trial left lingering doubts after his conviction and death sentence, which is under appeal.

But Teicholz’s account of the trial itself holds few doubts.

The evidence against Demjanjuk was overwhelming. He got a fair trial. He had no credible alibi, only that he was a former German POW who was being framed. Demjanjuk’s SS identity card, which the Soviets had supplied to the prosecution, belied this claim.

In the end, Demjanjuk couldn’t shake the identity card any more than he could escape those who providentially cheated death and condemned him.

They were as poignant and as powerful as the SS tattoo on his arm that he tried to scrape off.