Katie Hosteny isn’t fazed by blood spatters, digging through rotting garbage or crawling through putrid cars that once held corpses, but the clingy black powder she uses on everything sticks with her.

“You get really, really dirty with fingerprint powder,” said Hosteny, who dusts guns, bottles and any other evidence she can find with the carbon black-based substance. “If you blow your nose two days later, it will be black.”

It’s a small price, she says, to do a job that helps catch murderers, rapists and other criminals by finding fingerprints invisible to the naked eye.

Hosteny is one of 11 latent print examiners at the Seattle Police Department. The unit often provides detectives the critical link needed to catch suspects in high profile crimes.

That was true in the murder of a 46-year-old West Seattle woman who died from a blow to the head last December. Detectives suspected her ex-boyfriend, but he denied involvement and there was initially no evidence tying him to the crime.

The latent print unit was able to lift a print from a partially wrapped Christmas gift that put the former boyfriend at the scene. He confessed to the crime in March after being confronted with the evidence.

In another case, an examiner pulled a print from the window of a car involved in the murders of two men in Leschi in June. The print was matched to Ali Muhammad Brown, a homeless man also wanted on warrants for failure to register as a sex offender.

The print shifted the focus of the murder investigation to Brown and provided other clues that tied him not only to the killings here, but other crimes as well. Brown was arrested last month in New Jersey.

The latent print unit connects the dots for detectives in ways no one else can, said Lt. Michael Kebba, with the SPD homicide unit.

“Being able to put someone physically at the scene of a crime, by lifting their fingerprint, can be instrumental in solving a case,” Kebba said. “Particularly when a subject previously denied ever being present.”

Hidden prints

Most of Hosteny’s latent print work is done behind locked doors in a lab packed with high-tech equipment, including special lamps that emit light at different wave lengths and chambers that fog evidence with Super Glue.

The lab takes in thousands of pieces of evidence each year from detectives who hope the examiners can expose hidden prints that will help solve cases.

Hosteny, who is 32, dons a blue lab coat, purple gloves and ties her hair back in a ponytail when handling evidence. She has a drawer full of brushes made from feathers, hair, fiberglass and even a magnetic wand that’s used with metallic fingerprint powder. The main powder they use is made from a combination of carbon black and pumice. Hosteny dusts items with the clingy, black particles and then lifts exposed prints with tape.

She’s found prints on just about everything criminals might touch: steering wheels, windows, cigarettes, guns, eyeglasses, beer bottles, screwdrivers, poorly written notes from bank robbers, miles of tape – and even a Halloween pumpkin.

She recently dusted several different pieces of evidence including a crumpled Red Bull can from a burglary, a handgun from a robbery and a key chain from a car theft, pausing occasionally to fog evidence with her breath to “hydrate” the prints. “Latent prints are 99 percent water, so they are really fragile,” Hosteny said.

In addition to using fingerprint powder, the lab also has a refrigerator-sized machine with several chambers where examiners hang different items and fog them with Super Glue. Researchers in Japan discovered years ago that glue helps expose latent fingerprints.

After it’s dried, the evidence gets squirted with a yellow dye and then rinsed and dried again. Ultimately it gets taken into the most interesting part of the lab, a lighting room that features specialized equipment that emits light at various wavelengths.

Hosteny, wearing yellow-tinted goggles, held the Red Bull can under the light and a clear print highlighted by the Super Glue jumped out. A digital picture was taken of the print and then scanned into a computer and run for a match against a database of prints.

Finding a clear fingerprint is rare, and almost like Christmas morning, she said. “It’s really exciting. You want to get it over to the photo lab as soon as possible so you can search the fingerprint database and get an identification.”

No squeamishness allowed

The coolest part of being a fingerprint examiner, Hosteny says, is going out to crime scenes, hauling around a smudged fingerprint kit that’s crammed with gear including gloves, brushes, powder, tape and a really big magnifying glass.

“You’re at some unknown location. You have to assess the scene and document everything and then you are looking around and saying ‘Ok, where would they have touched,” she said.

The job requires curiosity, a knack for solving puzzles — and a lack of squeamishness. Before joining the police department, Hosteny had a job where she removed eyeballs from cadavers to be used for cornea and sclera transplants.

She recalls being called out to look for latent prints at a three-story town home where a woman was assaulted. Hosteny and her co-workers used a special chemical spray called amido black, which turns dark purple when it comes into contact with blood proteins, because “there was blood everywhere,” she said.

“As you keep touching things, the blood gets thinner and thinner. So you can’t really see the blood anymore but you’re still leaving behind prints,” she said, noting the chemical they used at the scene was able to expose them.

Other notable memories – digging through moist, rotting garbage for a bottle to process for prints, and the “pretty potent” smell associated with cars that held corpses.

Hosteny said she’s able to detach herself from the sometimes gruesome crime scenes.

“If it affected me and I had an emotional reaction, it wouldn’t be the right job for me,” she said. “It’s a job. You get in there and assess what’s going on.”