They're not packing .45s, they don't wear fedoras and none of them go by the name Spade or Columbo.
However, gumshoes at the Utah Department of Environmental Quality are tackling a mystery every bit as baffling as the Maltese Falcon."We've been out to the refineries three times, we've looked at propane distributorships, we've walked the natural gas pipeline and we've started looking at water treatment plants, and we're not finding an obvious source of the smell," said DEQ spokeswoman Carol Sisco.
That natural gas-like smell first billowed into downtown office buildings and Avenues residences on Thursday morning and returned on different occasions since, most recently Monday in south Davis County. Some people were sickened, and some institutions, fearing a gas leak, evacuated.
Now, sleuths are using a holster full of high-tech gadgetry to find out who is responsible for the stench that has plagued residents in northern Salt Lake County and southern Davis County.
On Monday, technicians with the Division of Air Quality and the University of Utah's department of meteorology began using computer models to reconstruct hour-by-hour wind patterns during the times the smell was reported. That wind data -- derived from monitoring stations throughout the valley -- will then be compared with the locations of 911 emergency calls that flooded police dispatchers when the smell was first noticed.
"We have these locations with clusters of (911) calls, like in the downtown area and Avenues neighborhood, about 10 a.m. Thursday," explained Patrick Barickman, an air quality monitor for the state.
"We are trying to reconstruct the wind patterns for that time. With the back trajectory of the wind analysis and the pattern of (911) calls, if it points back to the same area, it gives us information that can narrow down a likely source."
The accuracy of the computer model becomes even greater when wind data from the first instance are overlaid with those of subsequent reports. The more wind information and location data from the 911 calls that is entered into the model, the closer officials come to "finding a footprint of where the smell is coming from," Sisco said.
A cluster of oil refineries on the border of Salt Lake and Davis counties was initially believed to be the source since a black cloud caused by a burn off of excess butane and propane at the Chevron plant blew into downtown Salt Lake City on Thursday at the same time an odor caused evacuations of several downtown buildings.
Refinery officials have been working closely with DEQ since the smell was first reported. The state has monitoring equipment already in place around the refineries, but those devices did not detect a source for the odor.
State regulators visited the refineries on Thursday, Saturday and Monday, but tests again failed to detect a source.
On Monday night, investigators with the Environmental Protection Agency arrived with more-sophisticated testing equipment. Also on the case are the Davis County and Salt Lake County health and fire departments, and the state Division of Comprehensive Emergency Management.
"We are talking and coordinating so as not to duplicate our efforts," Sisco said. "Everyone is trying to find out what is happening, and we are looking at all kinds of industrial processes, not just the refineries. The smell could be from almost anything."
In other words, a foul deed has been done, there are plenty of suspects and slivers of evidence for case-crackers to follow.
"It is detective work," Barickman said. "Trying to figure out how done it."
Raymond Chandler, eat your heart out.