A 65-year-old McLean man who prosecutors have said was targeted for assassination after helping lure a fugitive former CIA agent back into the United States said yesterday that he may have been shot Sunday night because of his efforts to help government lawyers track another fugitive.

But Ernest R. Keiser, who was shot once at close range in the parking lot of a McLean restaurant, said he couldn't say for certain who was behind the shooting that put him in Fairfax Hospital the night before he was to go on trial in New York.

In a telephone interview from his guarded room at Fairfax Hospital, Keiser said his assailant grabbed a briefcase from him after the shooting that contained documents detailing the activities of fugitive financier Robert Vesco. Fairfax police said yesterday they could not confirm that statement, nor could they offer any explantion for the mysterious shooting.

Keiser, who describes himself as a former CIA employe, was put on a hit list after helping persuade former CIA agent Edwin P. Wilson to leave the safety of Libya. Wilson, now in a federal prison in Illinois, was convicted in New York last year of plotting to kill Keiser and seven others.

Keiser said yesterday he has been helping the government "in an effort to capture our man on the island of Cuba , Vesco" and said he believed Sunday's attack may have been related to those efforts and his knowledge of Vesco's "connection to certain people in the Bahamian government."

"I don't think it was Wilson," said Keiser, a McLean businessman, who was reported recovering rapidly from what officials described as a "superficial" bullet wound. " . . . As for Vesco, even that, I cannot say for sure . . . .

"But I've got to jump to conclusions. I cannot believe anybody would shoot somebody and take a briefcase if he didn't know what was in there."

Fairfax County police spokesman Sgt. Philip Lively said "the circumstances surrounding the shooting, in their entirety, are still under investigation." Police have recovered no weapon, no bullet and have no description of Keiser's assailant.

Neither police nor Fairfax prosecutor Robert F. Horan Jr. would comment on the briefcase being stolen, and police accounts of the incident made no mention of it.

A Justice Department spokesman said the federal government was monitoring the progress of the shooting case, but would not comment on it or Keiser's statements.

Keiser was scheduled to go on trial Monday in White Plains, N.Y., on a grand larceny charge. He has pleaded not guilty and he is also under federal indictment on a federal obstruction-of-justice charge in Tampa, Fla., scheduled for trial in January.

Keiser said he was meeting Sunday night at Charley's Place, 6930 Old Dominion Dr., with "the head of a private organization . . . in connection with the fugitive Vesco." Keiser said he left the restaurant to retrieve the briefcase from his car, and as he was leaning into the trunk someone "grabbed me, by my collar, and put an instrument in my back."

He said as he moved to turn around he was shot in the back on the right side, and as he fell, his assailant took the case from him. He said nothing else was taken.

Keiser said he collapsed and was found by a restaurant employe.

Prosecutor Horan said that the single bullet wound was "a contact wound," made with the gun in contact with Keiser's back.