The ShotSpotter analysis indicated that the first shot came from the location where DeOntÃ© had allegedly been on the minibike and that subsequent shots came from the general area where Haskel and Clay had been sitting in Haskel's parked SUV, the sources said.
The weapons, though not precisely identified by ShotSpotter technology, made distinctly different sounds, with Haskel's 9mm being the quieter of the two, the sources said.
ShotSpotter's ability to track gunshots can be impaired by unusual topography or high-rise buildings. But the sources said no questions have emerged about its reliability in determining the sequence of gunfire in a scenario such as the shooting of DeOntÃ©.
Big-city police chiefs say ShotSpotter not only alerts police to gun battles but also helps them piece together some perplexing crime puzzles. The technology is operating in 17 cities, including San Francisco, Newark and Charleston, S.C., and is being installed in seven more.
The FBI, which purchased the ShotSpotter sensors as a pilot project for the District, considers the technology so reliable that it has bought two more systems for cities plagued by violent crime and has plans to buy systems for other cities.
ShotSpotter spokesman Gregg Rowland said he could not discuss the details of the company's report in the Rawlings case. But he said the sensors provide an "important piece of the puzzle" for any investigation.
"We're like a live witness on the scene with very good eyes and ears," Rowland said. "Most police officers will match up our information with shell casings on the ground and any eyewitness testimony. When you add up A plus B plus C plus D, you can come to some conclusions."