Even with clean fingerprints and good DNA samples, criminal investigations often turn cold. But a recent study from the University of California, San Diego found a new way for investigators to narrow down suspect pools using chemical traces found on cellphones.

Scientists swabbed the hands and phones of 39 people, then ran the samples through a mass spectrometer, a fancy scale that measures molecules’ weight. The weight is used to identify substances using a reference database. It’s similar to the technology used when TSA officers swipe passengers’ hands for explosive residue. But instead of looking for specific substances, scientists tried to identify every chemical to create a lifestyle profile that tells us what the cellphone owner likes to eat, wear, and do.

“In the same way that a size 10 footprint at a crime scene may be useful information, we may be able to add, ‘This is the kind of shampoo this person uses; they like beer; [and] they spend a lot of time outdoors,’ ’’ said Pieter Dorrestein, a professor at the school’s Skaggs School of Pharmacy and Pharmaceutical Sciences and part of the study.

It could be useful in all types of cases, hot or cold.

Both the phones and their owners’ hands had similar lifestyle chemistries, meaning that phones found at crime scenes might be useful for describing a suspect’s or victim’s lifestyle. The results could indicate if a person of interest wore sunscreen and makeup, took antidepressants, or ate spices found in Indian and Mexican cuisine.

“I don’t think it’s possible to overstate how important this research is, even though it’s in its early days,’’ said David O. Carter, an associate professor of forensic science at the Chaminade University of Honolulu. “This is going into a whole different area of identification characteristics.’’

It’s the first time anyone has ever sketched a lifestyle profile using mass spectrometry, and scientists hope to test it on other objects, such as pens or handbags. The method alone can’t be used to identify an individual, but it could help investigators shorten the list of suspects in a less-biased way. Instead of describing someone’s hair, skin, or eye color, they can focus on their habits. “It’s data-driven as opposed to being driven by a personal profile,’’ Dorrestein said.

But matching the molecules to specific chemicals requires a robust reference database — one that is yet to exist, although Dorrestein and his colleagues are working on it. For a long time, scientists didn’t see a use for having an archive of random substances like potato molecules. Now, it’s valuable, especially when combined with other evidence, like DNA analysis or fingerprints. “A lot of forensic science boils down to having a good collection of things,’’ Carter said. “In many ways, a good forensics approach is to function like a museum.’’

With that said, scientists created meaningful lifestyle profiles by identifying just 2 percent of the molecules. With or without the larger database, investigators may already have something to run with.

Kelly Kasulis is a journalist living in Boston and the deputy digital editor of The GroundTruth Project. Follow her on Twitter @KasulisK.