NO ONE, perhaps, feels the state’s forensic crunch as acutely as Ken Martin. As forensic techniques become more thorough, the processes more elaborate, Martin has found himself spending more and more time at crime scenes. “It’s not uncommon for us to have two or three murders going at one particular time,” he says. “I might get called to a homicide in Fitchburg and not come home for 36 hours. I’m on call seven days a week, all the time. I was finishing up dinner on Saturday night and I got paged because we had a potential double homicide in Taunton. It’s inconvenient.”

Martin, a 17-year veteran of the Massachusetts State Police Crime Scene Services Section, specializes in blood-spatter analysis. Scenes that would make most of us run screaming for the hills are, for Martin, run-of-the-mill. As far as Martin’s concerned, a roomful of blood is nothing more than a kind of chart, to be interpreted and documented according to strict guidelines. It’s grueling, nitpicky work.

“When crimes of violence occur, many times blood is shed,” he says. “Blood being a liquid, as it is flying through the air it has to obey the laws of physics. As a result, you can apply those laws and determine what they call ‘points of origin.’ There are certain stains that are left behind. There’s a little tail that tells you which direction the blood was going. If you measure the width and length and put that into a simple trig formula, it’ll tell you the angle of incidence ...” And so on.

Trigonometric formulas notwithstanding, Martin essentially practices an interpretive art. As he scrutinizes a swash of blood, he will have a vision: the victim stood here, was bludgeoned once, twice, three times before staggering to this spot, where the assailant hit him again, and again, after which the victim fled down this hallway, arms flailing as he ran.... “He’s the expert,” says a colleague. “He’s the one that everyone comes to, from other states as well. He’s very well known.”

Even Martin’s considerable talents, though, have their limits. “When you get to the scene,” he says, “you are not able to say, ‘Listen, this guy is left-handed. Watch for the limp. He had surgery two weeks ago.’ I may be able to tell you whether the guy was flailing with his left hand or his right hand, but that’s it.”

Indeed, in stark contrast to CSI, there are few eureka! moments at a real-life crime scene. A scene can take days to process, and often requires examination by battalions of forensic specialists — anthropologists, orthodontists, chemists, toxicologists. Their work is tiring and stressful, fraught with the danger of dreadful bungles. One clumsy footstep, one ungainly elbow, can mean the difference between prosecution and washout. Beyond this, a crime scene is transient. Things dry up, rot. Insects, heat, and the size-11 boots of police officers can all conspire against the most diligent forensic investigator. This being so, investigators must work quickly as well as meticulously. As Lieutenant Martin puts it, “We only get one shot at this.”

Once Martin and his colleagues have processed the crime scene, the evidence they have gathered is packed into pizza-box-size containers and transported to the Sudbury-based crime lab, where a staff of highly trained technicians subject it to a battery of tests. All the while, the “chain of evidence” (who touches what and when) must be carefully documented. “It has to be an exact science,” says Martin. “Otherwise we couldn’t testify.”

Even so, defense lawyers still question the reliability of physical evidence. And when they do, they don’t take aim at the white-coated technicians who move among the thermal cyclers and genetic analyzers of Selavka’s lab. Instead, they go for the foot soldiers — those who work the crime scenes. Which, of course, makes perfect sense.

A crime scene is, by its nature, a messy, chaotic environment. Imposing order and certainty on such chaos is always a tricky proposition. And a good defense lawyer knows how to exploit this fact. “I just testified yesterday in a case of blood-spatter analysis,” says Martin, “and naturally, the defense attorney will always challenge you, because that’s what he is being paid to do.”

But CSI work is not only stressful: it’s dirty, dangerous, and — it has to be — depressing. When Martin kneels beside a corpse with a screwdriver protruding from its neck, he tries to focus his attention on the type of screwdriver, the angle of entry, and the depth of the wound, but there’s no getting away from the fact that this is a little piece of hell he’s dealing with. A crime-scene investigator’s career revolves around misery, cruelty, and despair. Nowhere is this fact more apparent than in the office from which Martin works — the chief medical examiner’s office in Boston.

Like every other branch that works with forensic science, the medical examiner’s office must deal with the challenges that technological advances have ushered in. “Advanced testing can take more time, can require specialized training and specialized personnel,” says the chief medical examiner, Dr. Richard Evans. “It can be stressful,” he adds, “but our specialized training in the field has helped to prepare us.”

Regardless of the municipal polish of the place and the no-nonsense practicality of its employees, the ME’s office is a house of horrors. There are gray chambers of concrete and steel, floors that funnel into drains. There are bones lying about, black blood stains, jars containing bits of brains, pickled bile. There is a barrack of body bags, laid out in rows; one bag shows red through the white plastic. Nearby is the so-called deco (short for “decomposition”) room, which contains a single body bag — or body sack. A small, edgy ME appears. “Young man with AIDS,” he says, nodding at the sack. Then he groans, literally groans out the words: “I’m plucking up the courage to go in and do the examination.”

The most disturbing room in the whole complex, however, is actually quite nice, like something you’d find in a mid-range hotel. The room doesn’t have the cloying, sweet-and-sour smell that fills much of the rest of the building. It contains a pink rug, upholstered chairs, a TV in the corner. The far wall has a curtain. Martin draws it back to reveal a thick-paned window, beyond which is a small, gloomy booth containing a single metal bench. This window is where family members stand and scream, sob, swoon, swear, vomit, disbelieve. Dealing with this sort of thing day in and day out must take its toll.

“To me it’s a job,” Martin says, sitting a matter of feet from the seething deco room. “You have to dehumanize [the victims] or I assume I would have gone crazy by now. I process the bodies for trace evidence. We’re looking for how the crime was committed. Everything has to add up. I’m looking to the science part of it. The answers. I’m being objective.” He pauses for a moment. “Sometimes you feel sad. Some of the cases that you’ve seen, if you think about it, if you contemplate it, it will make you sad, if you sit back and think about some of these situations.” He pauses again. “Homicide is never really a happy subject.”

Chris Wright can be reached at cwright[a]phx.com.