Written in blood

Crimson drops slip off the tip of a knife. Scarlet liquid spurts from an artery. A fine red mist escapes from a dying breath.

Jeff Gurvis paints rooms with real human blood, yet never harms a living soul.

As a leading expert in bloodstain pattern analysis -- please don't say blood splatter, it sounds so sensational -- Gurvis creates mock crime scenes in buildings around the suburbs and the nation.

Using a blood-covered target to simulate the victim, Gurvis slashes with a knife, swings a baseball bat or squirts a syringe to mimic the many ways blood can be spilled.

Using expired donations from blood banks, Gurvis has staged his macabre scenarios in expensive North Shore homes due to be torn down. He also takes his show on the road, giving seminars across the country in condemned buildings. He even runs tests in the garage of his home in Vernon Hills.

His students -- police officers and forensic scientists -- explore his bloody creations to figure out how a crime might have taken place.

The classes reflect Gurvis' real-life experience.

A former crime-scene coordinator for what's now the Northeastern Illinois Regional Crime Lab in Highland Park, Gurvis has worked on everything from burglaries to murders.

A leader in the field at age 37, he's even come up with his own theory of how blood gets scattered from a weapon.

For Gurvis, the beauty of blood is that it catches perpetrators in the act.

Fingerprints and DNA can tell who was present at a murder scene, but blood patterns reveal how the act was committed. That can help answer crucial questions like: Was it homicide or suicide? Self-defense or premeditated murder?

After a suspect has been identified, blood patterns help determine whether events happened the way he or she said they did.

Sometimes, that's enough to put a killer behind bars.

Who shot whom?

Take the case of Christopher Vaughn, the man accused of shooting and killing his wife and three children June 14 in Will County.

Vaughn, who had a gunshot wound to his leg, told police his wife shot him and the children before committing suicide.

Blood pattern analysis, Gurvis said, will be crucial in determining whether Vaughn is telling the truth.

Investigators have an advantage because the crime occurred in the enclosed space of a sport utility vehicle. Most of the blood evidence should be captured inside.

Though he is not involved in the matter, Gurvis knows how such an investigation proceeds.

Investigators locate, plot and photograph the blood, identify the types of patterns it created, then match those patterns to where they came from.

To locate the point of origin, the tail of any projected blood streak will point like an arrow in the direction of travel. Tracing it back the opposite way shows where it came from.

By dividing the width of the blood streaks by their length, an investigator can calculate the angle the blood traveled. Run strings back from all the spots of blood, and they should converge at the point of origin.

Once the blood patterns and sources have been established, investigators will try to determine the sequence of events -- and that's when the work gets interesting.

Footprints, handprints and streaked blood indicate movement after the initial attack -- perhaps an attempt to change or hide evidence.

For instance, victims who die instantly where they are don't leave footprints around the crime scene. Perpetrators might.

Back spatter from gunshot entry wounds can also leave telltale marks on the hand or clothing of the shooter or the seat belts, windows or other surfaces around him or her.

Investigators will also look at where there is not blood. If there is no blood on a surface next to the victim's wounds, for instance, the void might indicate the shooter's arm or other body part was in the way.

With information on ballistics and firearms, analysts might establish where the shots were fired and whether anyone had gunpowder burns on his hands. Gurvis anticipates such physical evidence might make or break a case.

He should know. He's used such methods to crack cases himself.

CSI: Sherlock

Gurvis wasn't particularly interested in blood as a child -- but he was fascinated by Sherlock Holmes. By age 13, Gurvis had high marks in math and science and thought forensics would be a rewarding way to apply his skills to the real world.

He confirmed it was the career for him when he went to a class on blood pattern analysis in Las Vegas and didn't spend a single quarter on the slots -- he was too busy studying.

Gurvis got a degree in forensic science and an MBA, then got a job with what became the Northeastern Illinois Regional Crime Lab, which collects and analyzes evidence for police departments across the suburbs.

One of the most well-known crimes Gurvis worked on was the murder of Olamide Adeyooye, a student at Illinois State University. Her body was found burned in Mississippi in 2005.

Gurvis helped corroborate investigators' theory that the victim was attacked at home, by finding she coughed up a fine mist of blood in her apartment.

A bloody fingerprint tied the suspect to the scene. Thanks in part to the evidence against him, the man pleaded guilty and is serving life in prison.

Gurvis has used his skills to help exonerate an accused man and to implicate a man despite his release for alleged wrongful imprisonment.

Gurvis has also taught blood pattern analysis at FBI headquarters in Washington, D.C., and at the National Forensic Academy in Tennessee, where real cadavers are used to teach forensic investigation.

He now works for Porter Lee Corp. in Schaumburg, implementing software for law enforcement agencies to manage evidence.

But he still specializes in ways to decipher the hidden meanings of blood patterns.

One type of blood stain that's always posed problems for analysts is a cast-off pattern: blood that's spun off from a weapon, an arm, a wheel or anything that moves in an arc.

In response, Gurvis and a collaborator are using a basic tool of blood pattern analysts -- trigonometry -- to come up with a new theory to determine the origin point of any swinging object that casts blood stains.

The theory was presented at last year's International Association of Bloodstain Pattern Analysts, and is now being tested by researchers in New Zealand. If it passes muster, it will be published and could help investigators figure out what size and kind of weapon a killer used.

Gurvis has worked to stay professionally detached while witnessing the aftermath of murder -- ever since his first violent crime scene, a man who'd been beaten to death.

"I really tried to prepare myself before entering the scene," he recalled. "I moved very slowly. However, once I did see the body, it really was no big deal from a horror standpoint. What surprised me was how nonlifelike the body looked. Dead people look more like mannequins than people.

"Once you cross over that realization, you are focused on the task at hand … The important thing is that scientists must separate the human element in order to remain objective."