Virginia State Police arrested a 20-year-old Brunswick, Md., man early today and charged him with murder in the death of state trooper Leo Whitt, who was shot Friday evening during a routine traffic stop on I-95, police said.

Whitt, 48, had his gun in his holster when his body was found, Col. Robert Suthard, superintendent of state police, said here today. "There's every indication that he had no opportunity to respond."

Gregory Warren Beaver Jr. and his companion, Andrew Peter Sanborn, 24, of Haverhill, Mass., were arrested about 3:50 a.m. today near a fast food restaurant in the Richmond suburb of Henrico County.

Beaver had first identified himself to police as Kester E. Lowers Jr. and refused to gave a home address. State police spokesman Charles Vaughan said authorities determined through fingerprints and a photograph flown from Maryland that Lowers was an alias and that Beaver was being investigated as a possible suspect in a Maryland robbery.

Vaughan said police were checking reports that Beaver may have escaped from a drug rehabilitation program in Arlington and may be wanted in other states.

Arlington prosecutor Henry Hudson said there is no residential drug program in the county, nor is there any record that Beaver has ever been prosecuted there.

Sanborn was charged with grand larceny of an automobile, Suthard said.

Whitt, a 21-year veteran of the force, was the second state trooper to be killed since Dec. 18, when an officer was slain near the West Virginia border. Sgt. J.L. Biggs was shot in the chest after he stopped a car for a traffic violation.

Whitt apparently was shot twice with a handgun at about 9:30 p.m. Friday while patrolling alone in Prince George County, Va., on I-95, about 35 miles south of Richmond, Suthard said. He died at the scene. Suthard said a passing motorist from Maryland notified authorities.

Vaughan said Sanborn went into a Hardee's restaurant just outside Richmond several hours later and told employes the man he was traveling with had shot a policeman. It could not be determined whether Sanborn or an employe actually called police, Suthard said.

Beaver was being held under $1 million bond. Sanborn's bond was set at $50,000.

The two men had been traveling in a 1978 Camaro with a temporary Florida license plate, Vaughan said. The car was stolen, Suthard said, and police found one weapon, which he could not identify.

Whitt lived in Prince George County with his wife. He had two children. Whitt "was a quiet, easygoing, dedicated state police officer," Suthard said.