They take ear prints off doors. They lift shoe prints off banana peels. They can tell what someone was hit with simply by looking at the bruise left behind or how long a body has been dead.
They are the nation's top forensic scientists, and many are gathered in Salt Lake City this week.
For the first time, Utah is hosting an "education conference" of specialists from a variety of forensic disciplines.
The conference at the Red Lion is presented by the Utah Division of International Association for Identification and the Northwest Association of Forensic Scientists. Some of the sessions that contain sensitive investigative information are closed to the public.
From Utah, the Destiny Norton murder and the Trolley Square massacre were discussed during a closed door session. Police detectives and experts from the Utah State Crime Lab discussed how evidence was collected and processed during the Norton case, said Utah IAI president and West Jordan police detective Francine Bardole. Those involved with the Trolley shootings discussed how four separate crime scenes all related to the same incident were processed.
Michael Grimm, who worked for nearly four decades with the FBI and Virginia's Department of Forensic Science before recently retiring, said the advancements in forensic technology have led to countless arrests across the country. That's important, he said, because there is no room for error in his line of work.
"We don't make mistakes. If we make mistakes, in most cases it costs us our jobs," he said. "We're not allowed to make mistakes. If we were to falsely identify someone it could mean false imprisonment and, in some cases, death."
Grimm is a skin impression expert. During his "Marks of Madness" presentation Tuesday, he talked about how just about any body part or weapon leaves identifiable impressions.
"Most people think of fingerprints as being the only unique part of the body for leaving impressions," he said. "All body parts are unique. Most of them, however, are left on surfaces not sufficient to recover. Lips and ears are also unique. Even our knuckles are unique."
Grimm received some national attention a few years ago when he was able to help capture a Peeping Tom by lifting the lip impressions the man left on a woman's window. It was a case that even gained attention in Playboy magazine, Grimm recalled.
In another case, Grimm helped bring a man into custody by taking the impression of an ear off a door. The suspect had pressed his ear against a door before breaking in to see if anyone was home, he said.
"It left a very significant impression on the door. There were very minute characteristics on the outer edge of the skin left on the door," he said.
Just this past August, Grimm helped to positively identify the body of a man who died in a plane crash in 1948. Using special chemicals from George Washington University, Grimm was able to rehydrate the victim's skin and lift prints. The result is believed to be the oldest post-mortem identification in history using fingerprints. Although there have been cases of forensics experts obtaining evidence from people who died much longer ago, such as mummies from Egypt, Grimm said because of fingerprint database systems, this was the first time an individual had been positively identified.
The case was still so new that Grimm could not reveal other details about the incident Tuesday because the victim's next of kin hadn't even been notified yet.
Grimm was recruited by the FBI right out of high school in 1968. Back then, he said, there were hardly any forensic scientists.
"At that time there was a shortage of employees," he said.
One of his first jobs was identifying unknown deceased U.S. soldiers from the Vietnam War, he said.
"When I first started in fingerprints, everything was done manually," he said. "Now in the day of computers we have automated fingerprint systems. A single latent print can be compared in a matter of seconds."
Not only has the technology changed, the field of forensic science has also boomed in popularity because of TV and the movies.
"There was never the interest there is now," he said. "We call it the 'CSI effect."'
Now the workforce has more applicants than positions. But Grimm said it has also provided for a much better pool of talent for law enforcement agencies.
Many of those new forensic scientists get their training at a facility that has received worldwide attention known simply as "The Body Farm."
The Body Farm, or the Anthropology Research Facility of the University of Tennessee, Knoxville, is an outdoor facility that gives students hands-on training in the study of crime scenes, specifically murders. Real cadavers donated to the school are placed in every imaginable situation in the outdoor training facility.
Law enforcers are taught such things as the different stages of decomposition and how to unearth a body and still preserve it.
Nathan Lefebvre runs the University of Tennessee's National Forensic Academy. He works with The Body Farm, running 10-week courses that train law enforcers from all over the nation. The program has become so popular that the waiting list to get in currently extends into the fall of 2009.
"I loved it. I learned so much. A lot of hands-on actual experience. You learn how to do things and precisely how they need to be done. There's no place in the world like it," Bardole said.
"We take them step-by-step through all the different types of crime scenes," Lefebvre said. "We've burned down a house.... This Friday we're blowing up a car and students will have to work that scene, the type of bomb and origin will have to be determined. It's the only place in the country that provides that type of intense forensic investigation training."The 10-week course is funded by the Bureau for Justice Assistance, said Lefebvre, who is in Salt Lake City this week for the conference.