Car-Crash Investigators Partner With Computers

The Mercury's driver, John C. Johnson Jr., was on his way to pick up his sister from work when the crash occurred, sending his car skidding 150 feet down the road and over a patch of grass. Johnson, who was described by relatives as a good-hearted man who always put family first, was killed almost instantly.

His Mercury was crumpled -- the driver's side crushed, computer components and wires dangling from the dashboard, the remnants of an air bag and metal jutting in all directions. The Buick's front end was smashed.

In an interview later, Miller described what he did at the scene. After a quick scan of the intersection, he took out a laser device known as "Total Station," which works much like a surveying tool. For several hours, Miller shot the laser from a specific point to a prism being held by a police technician, allowing him to quickly tabulate distances and carefully map the scene.

He marked skid marks, debris fields, furrows in the grass, trees, streetlights and even bushes. Without the laser, Miller and the technician would have spent four hours evaluating the scene with tape measures and calibrated wheels. Once the information was uploaded into a computer, it would generate a map of the scene, showing the precise location of each object.

Based on the preliminary examination, police arrested the Buick's driver, Guy B. Agnant, 22, of Lanham, and charged him with second-degree murder and illegal possession of a handgun, which authorities said was found under the front seat. The case later went to a grand jury, which returned an indictment on murder and gun charges.

Agnant, who was seriously injured in the wreck, pleaded not guilty to the charges and is awaiting trial in D.C. Superior Court. He is under house arrest as he recovers from his injuries, said Robert C. Bonsib, Agnant's defense attorney.

Bonsib said he and his client would not comment because the case is pending.

Despite all the work done at the crash scene, Miller had plenty of additional investigation to complete before the prosecution moved forward. In early February, as he handled a half-dozen other cases, he jumped back into the probe. Accompanied by a Post reporter, he visited the city's impound lot, took laser measurements and closely inspected the two mangled cars.

Using the laser device, Miller and Officer Anthony Maturo, a crime scene technician from the Secret Service experienced in fatal crashes and assigned to the case by the U.S. attorney's office, measured the dents in the cars. The measurements later would help Miller more precisely plot the cars on a map showing their locations before, during and after the collision.

That week, Miller and Maturo also had a tow truck put the cars together, as if at impact. They then took some overhead photographs to show how the cars fit together.

The detective then removed the black box -- actually silver, in this case -- from the Buick's center console. The device helps deploy the car's air bags and monitors various systems. During a crash, it collects the last five seconds of data -- ranging from the car's speed to its throttle position -- and locks the information into its memory.

Most General Motors and Ford vehicles carry such recorders. About 33 million cars on U.S. roads, or 15 percent, have them, according to the automotive industry. But this was the first time that Miller had used one to investigate a fatal wreck. It is also the first time that D.C. prosecutors intend to use the device's data in a criminal case, authorities said.

On a snowy February morning, a week after visiting the impound lot, Miller and Maturo drove to Fairfax, which has the software and equipment required to read event data recorders. Miller said D.C. police are trying to buy such software but have been unable to come up with the funds.

The Fairfax officers plugged the device into a laptop computer, which quickly hummed to life.

A graph popped onto the screen. It showed the Buick going 81 mph about five seconds before impact. The instant before the crash, the Buick was traveling 91 mph.

Miller began to ponder the meaning behind the new data, which showed the Buick accelerating, not slowing, before impact. Miller and the other officers quickly theorized that the driver was hurrying to make it through the intersection before the light turned red. It was a detailed piece of evidence that Miller said was not available in the past.

Miller took a breath and smiled. His previous work had been amazingly accurate.

"It's one table leg of the entire investigation," Miller said of the black box.

Then he began talking more like an engineer and less like a police officer: "When you put it all together, you have a very stable platform that shows how the crash occurred and why it occurred."