BOOK REVIEW / MYSTERY : Post-War Tucson Murder Mystery Oozes From Concrete to Abstract : VERSIONS OF THE TRUTH <i> by Richard Parrish</i> ; Dutton, $20, 320 pages

Exactly how tough is Joshua Rabb, the hard-boiled hero of “Versions of the Truth,” a mystery novel set in postwar Tucson?

He’s so tough that he uses the stainless-steel pincers of his prosthetic arm to kill a man by crushing his Adam’s apple, and when Rabb speaks out loud to God in a Tevya-like plea for divine intervention--or at least a break in his most perplexing case--Rabb simply cannot control his temper.

Now that’s tough.

“Versions of the Truth” may be the only mystery in the history of the genre in which the central plot focuses on the construction of a sewage system. It’s 1946, and cholera is killing the Papago Indians on the big reservation near Tucson.

The only way to stop the epidemic, we are told, is to build a sewage treatment plant in the nearby Mexican border town of Nogales. And the rival construction magnates bidding for the job are perfectly willing to cheat and kill in order to win the big contract.

Rabb is a transplanted attorney from Brooklyn who works for the Bureau of Land Management and practices law on the side, and his job is to find out who is cheating and killing whom: Is it the aging land baron who is so generous with his horses and his women? Or the beautiful young woman who is either the land baron’s niece or a hooker from Kansas City? Is it a pair of war profiteers whose construction business has fallen on hard times now that the shooting is over? Or the governor of Sonora, a potentate with an army of pimps, thugs and crooked cops at his command?

Now, as it turns out, a good deal of the plot turns on the finer points of government-contract bidding procedures and the difference between Type 2 and Type 5 concrete, but Parrish succeeds in livening up the story with lots of sex and violence. The lovemaking, I’m afraid, seems dutiful and even mechanical.

But Parrish really lets his imagination soar when he describes the parade of horrors that Rabb encounters in his investigation of the concrete scandal and his law practice--the author seems intent on packing his book with graphic violence of the most gruesome kind, and the victims include a household pet, a 12-year-old boy and even an infant.

Parrish styles Joshua Rabb as a man with an engaging blend of book smarts and street smarts, a sensitive guy with an unmistakable taste for rough justice. Rabb is a World War II combat veteran who lost his arm and four toes before V-E Day, and now he puts his mechanical arm to good use as a weapon.

When his young Papago housekeeper gets pregnant, Rabb is helpfully pro-choice, even if it means breaking the law. And he reads “Siddhartha” in his spare time.

Tough and savvy as he is, though, Rabb cannot help stumbling into various social, cultural and political minefields that litter the old (cow)boy network of Tucson and the Papago Indian Reservation, all of which Parrish renders with great credibility and conviction.

And, rather like the pointedly stupid people who populate horror movies, Rabb allows his children to wander at will around Tucson and environs even after someone has broken into the family home and redecorated it with dismembered body parts.

“Versions of the Truth” is the second Joshua Rabb novel by Richard Parrish, himself a practicing attorney in Tucson. Like most attorneys-turned-novelists, Parrish seems to shy away from writing about what lawyers actually do , and instead he sends the Levi’s-clad and boot-shod Rabb on a series of high adventures that keeps him far from the courtroom. Only once does Rabb crack a lawbook, and he never seems to spend much time preparing for the murder trial that is the major subplot of the book.

Still, to his credit, Parrish is willing to confront the moral compromises that one is required to make in the practice of law. He gives Rabb a couple of clients from hell--a retarded youth who sets an ostrich on fire, and a sociopath accused of raping and murdering a young mother and her month-old baby--and then shows how Rabb is willing to use his considerable skill and ingenuity on their behalf even though he knows that they are guilty.

“How can you defend an animal like that?” scolds his 14-year-daughter when she learns that her father will represent the accused rapist-murderer. “It isn’t right.”

“I’m a lawyer, honey,” he says. “That’s what I do for a living.”

It’s not entirely clear whether this is intended to be a laugh line--Parrish is mostly earnest and solemn about the woes that befall his lawyer-hero, and he brings the whole affair to rather dark and fatalistic climax.

But there’s enough suspense here, enough shocks and surprises, to keep us reading until we find out the fate of the ostrich-arsonist and the baby-killer, and even the big question of exactly how much tricalcium aluminate was in the concrete for the Nogales project.