A Fairfax police investigator testified yesterday that two Clinton men who allegedly were paid $3,500 each to kill a service station operator in a murder-for-hire plot shot the victim after failing in an attempt to knock him out with chloroform and slit his throat.

Investigator Guy Boggess testified in Fairfax County General District Court that James T. Clark Jr. and Charles D. Stewart, both 21, killed George H. Scarborough, the gas station owner, as he walked in the front door of his townhouse at 6541 Yadkin Ct. in the Franconia section of the county on Jan 31.

Police have said that the two men were hired by Scarborough's 44-year-old estranged wife, Jamie A., to kill her husband.

Both Mrs. Scarborough and Betty M. Holler, 37, of 416 N. Howard St., Alexandria, also have been charged with murder in connection with the crime.

At yesterday's preliminary hearing for Clark and Stewart, Boggess said Clark told him that he and Stewart were together at a Maryland residence in January when they received a telephone call from a woman named "Betty."

Boggess said the woman, who police have identified as Betty M. Holler, asked the two men if they were interested or knew of anyone who would be interested in doing a "contract hit" for $3,500 each. The men set up a meeting next day with "Betty" to talk about the contract and who was to be killed, the officer said.

Boggess said that at the meeting the men were given Scarborough's home address and his service station address on Backlick Road in Springfield. They went to the addresses to make sure that they knew who they were to kill, the officer said.

Three days before the murder, the two men went to the Shirley Duke shopping center in Alexandria, where they received $1,200, the detective said. He didn't say who gave the men $1,200.

On Jan 30, the two men went to Scarborough's home, but the hit "did not go down," as planned, Boggess said.

Boggess said the men returned the next day, broke into Scarborough's townhouse and waited for him. While they were waiting, they ransacked his home, he said.

Scarborough arrived home about 9.45 p.m. and as he walked in the door. Stewart grabbed him and "tried to chloroform him and slit his throat," Boggess said.

He said Scarborough was so strong that Stewart couldn't overpower him. At that point, Clark walked up to Scarborough, pulled out a small caliber pistol, and fired four or five shots, the detective said.

The men then fled to a Maryland Street, Boggess said. The other woman was later identified as Scarborough's estranged wife, he said.

"A week or two weeks later," the two men met "a lady and Betty in a yellow car" in a parking lot off Duke Street, Boggess said. The other woman was later identified as Scarborough's estranged wife, he said.

The two men and the two women went to the back of the parking area, where Stewart went into a building and came out with an enveloped containing $5,800, Boggess said. He said the men split the money.

Both men were arrested last month, Stewart in Miami and Clark in Los Angeles. Each has been charged with murder for hire and the use of a fire-arm in the commission of a felony. The maximum punishment is death.

Judge Lewis H. Griffith yesterday sent their cases to the grand jury.

The arrests of Stewart, Clark, Scarborough and Holler came after Fairfax police arrested two other men on extortion charges in May.

Those men, Daniel M. Coleman, 22, of Castle Hayne, N.C., and Robert C. Ogden, 43, of Waynesboro, Va., were arrested after Jamie A. Scarborough told police that extortionists had threatened to harm her 14-year-old son unless she dropped off $5,000 at the Springfield Mall.

Coleman and the two Clinton men are acquaintances, police said.