Tales From the Crypt : HOMICIDE: A Year on the Killing Streets; <i> By David Simon</i> ; <i> (Houghton Mifflin: $22.95; 602 pp.) </i>

This book has a huge cast of characters, most of them corpses.

They are murder victims and we, like the author, meet them after the fact. The bodies, lots of them, 115 to be exact, include cocaine dealers, drug users, thieves, streetwalkers and the occasional innocent victim. Young and old, black and white, male and female, they are casualties of the holocaust on our streets.

The locale is Baltimore, but the bad things people do to each other are universal. This could be any big city with its ghettos, stifling summers and unpredictable outbreaks of murderous violence. The year is 1988, when Baltimore recorded 234 murders. Author David Simon, age 30, after four years on the police beat, took a leave from the Baltimore Sun to spend a full year shadowing homicide detectives, seeing the city and their job through their eyes.

Though the book lacks the riveting sense of high drama that will keep readers breathless and awake, turning pages far into the night, that is precisely the point. Detective work is methodical and plodding in real life, with success almost always attributable more to luck and a gritty determination than to any investigative genius. Police work is 99% routine and 1% excitement.

No single hero dominates this book; there are 19: a lieutenant, two sergeants and 16 detectives, an entire Baltimore PD homicide shift. All men. The villains are everybody else. The bad guys include meddling police brass, lying suspects, conniving witnesses, interfering politicians, lazy juries, even pushy news reporters.

Watching real homicide detectives at work always is fascinating. A special breed, they are raucous, loud and profane, and without doubt performing some of their raw banter for the benefit of their biographer. Simon dutifully records without comment the detectives’ sexist attitudes, as they disdainfully dismiss women police officers as “secretaries with guns.� Except for a female detective briefly mentioned as accepted in spite of her sex, the only women police we are told about are cowardly or inept, such as one who picks up a bloodstained murder weapon, then vacuously asks, “Is this important?�

Too bad for Baltimore. One of the best homicide cops I have ever met is a woman.

The book, though stylishly written, contains disappointing factual errors embarrassing for a reporter. Explaining major changes in the department, Simon describes a bad shooting by a Baltimore policeman in March, 1980. He writes that it “came only weeks after a similarly questionable shooting by a white officer had sparked race riots in Miami.�

The Miami riots did not take place until May, 1980, and they were not related to a shooting. They erupted after a jury acquittal of white police officers accused of fatally beating a black motorcyclist.

Simon’s concept of age also is slightly askew. He refers repeatedly to a 51-year-old suspect and a victim, age 50, as “old� men, then calls two youthful suspects, a 10-year-old and a 13-year-old, “the two teen-agers.�

The author does succeed in exposing the hearts of his homicide cops. Revealing, even touching, is the confession of an otherwise blasphemous and blustery detective who gruffly acknowledges his belief in God and a heaven. This man who deals daily with death is convinced because all those corpses seem so empty. They are only shells. What is missing cannot simply disappear, they have to go someplace.

Simon has captured the poetry of the meanest streets and composed his own 10 Rules of Urban Homicide Investigation. No. 1: “Everyone lies.� Murderers lie because they must, witnesses because they think they have to, and everyone else lies for the sheer joy of it.

He shows us how the Miranda decision has forced detectives to become ingenious, devious and deceitful, manipulating suspects into relinquishing the rights they are advised about. Without such hypocrisy, the author truthfully reports, a lot of guilty people would go free. “Homicide� also is a handy guide on what not to do or say should you be suspected of murder.

The book’s most important and frustrating mysteries are never neatly wrapped up. In real life, and especially in our justice system, there are few, if any, satisfying endings. The rape-murder of 11-year-old Latonya Wallace and the case of a young man shot in the back while fleeing a stolen car go unsolved despite heroic efforts by talented investigators, proving another of Simon’s 10 rules: “It’s good to be good, it’s better to be lucky.�

Homicide detectives tell the world’s best war stories. They are certainly noble creatures when at their best. These men are so intriguing, their mission so vital, that a reporter must use caution. You must not be caught up in their charisma and their thinking, you must not become one of them.

They can reel you in just as they do their suspects. To a great extent, that is what we witness here, the metamorphosis of the author from reporter to policeman. Simon cuts his hair, removes his diamond-stud earring and changes the way he dresses in order to be accepted by these macho cops. The changes do not end there. Soon they are drinking, cursing and thinking alike.

These tough guys harbor no sympathy, even for a dead baby. Homicide cops who daily face a job like no other must grow calluses on their hearts to survive. Without the black humor that makes them laugh, they would surely cry. Their seeming insensitivity is a shield, a defense mechanism understood by those who know them.

But we journalists have no excuse for similar behavior no matter how much male camaraderie it may evoke. It troubles me when Simon refers to a man who burned to death as “a crispy critter.� Sure, cops talk like that all the time, but not us. In the next paragraph Simon describes the scene: “The poor bastard is lying there like a piece of chicken that someone forgot to turn over.�

By the last page, Simon is shoving a suspect up against a car and frisking him. Realizing that he was crossing the line, he acknowledges that it was a good thing his year with the cops had ended. Maybe his new tough-guy techniques will come in handy in the newsroom--in his next encounter with a pesky editor.