By Philip P. Pan
Washington Post Staff Writer
Thursday, September 10, 1998; Page D05

Prince George's County detectives investigating the fatal shooting of a commuter on the Capital Beltway sought the help of Washington's five cellular phone companies yesterday in locating the unidentified motorist who reported the slaying but then disappeared after his 911 call was cut off.

Even as they interviewed a new witness who provided a description of the suspect's vehicle -- but not of the shooting or the suspect -- detectives prepared to subpoena the phone companies and ask them to identify the man who called 911 and described seeing someone lean out a car window and fire several shots at a car to his right about 5:30 p.m. Friday.

The shooting occurred at the height of rush hour and at the start of the Labor Day weekend on a congested stretch of the Beltway's outer loop just north of the Pennsylvania Avenue exit. Nevertheless, only two drivers have stepped forward to help detectives, including the witness who came forward yesterday, and neither saw the actual shooting.

"There's got to be more people out there," said Lt. Michael McQuillan, the homicide commander. "Hopefully, with these appeals, people will continue to come forward. We'll do what's necessary to maintain their safety."

The lack of witnesses means the 911 call is the only account police have of the events leading to the death of Charles Frederick Carson, 33, of District Heights, who was heading home from his computer job in Alexandria when he was gunned down in the far-right lane.

During the crucial, frantic 911 call, a man told police that he saw Carson's car veer off the highway and that he still had the suspect's vehicle in sight. But then, according to Maryland State Police, the call was disconnected, apparently because the phone's cellular connection was lost.

In addition, only the first portion of the call was tape-recorded because of a communications malfunction at the state police barracks in Forestville, authorities said. As much as a minute may have been lost, according to one state police official.

A Prince George's 911 operator was the first to answer the call, and that portion of the call was recorded. But after only a few seconds, the call was transferred to state police, which has primary jurisdiction over the Beltway, authorities said.

Neither the state police dispatcher nor the county 911 operator obtained the caller's name or phone number before the line went dead, authorities said.

Police have not determined a motive for the crime, and are investigating whether it might have been an act of "road rage."

The county's 911 system automatically records the phone number and originating address of all calls from normal telephones. But like the vast majority of 911 systems in the nation, it is not equipped to provide any information about calls from cellular phones.

Officials with cellular companies in the Washington area said they should be able to identify the 911 caller for police, given a court subpoena and some time to search their databases.

Police have described the suspect's vehicle as a large, old-model vehicle, possibly a tan-colored Ford LTD with tinted glass. Carson was driving a light brown 1991 Acura Legend. People with information have been asked to call 301-735-1111 or 301-772-4925.