Rosey Grier, the former Los Angeles Rams lineman who was Sen. Robert F. Kennedy's unofficial bodyguard the night Kennedy was fatally wounded in 1968, is coming out in support of President Carter's reelection, a Carter-Mondale source said.

So is former Washington Redskin Ray Schoenke, another longtime Kennedy family loyalist who helped Ethel Kennedy stage her annual pet show at "Hickory Hill" and ran the Joseph P. Kennedy Foundation Special Olympics in 1969.

Schoenke is chairman of the newly formed "Artists and Athletes for Carter-Mondale," which plans to announce its membership next week.

Schoenke refused to talk about his defection from the Kennedy ranks last night, except to confirm that he has done so and is heading the committee. He would not discuss his ties with the Kennedys. "Ethel isn't running for the presidency," he said.

Grier couldn't be reached for a comment.

If there are still mysteries about Chappaquiddick to be solved, one of the principals has just gone to work for the one private intelligence agency that might be able to solve them.

Paul Markham, the former U.S. attorney who was with Sen. Edward M. (Ted) Kennedy the night Mary Jo Kopechne died, became a vice president of Intertel Jan. 1.

Intertel, one of the world's largest intelligence and security networks, was the envy of the Nixon administration even before Watergate because the Republicans considered it "Kennedy Mafia dominated."

It is headed by Robert D. Peloquin, who was a member of Bobby Kennedy's "Get Hoffa squad" at the Justice Department.

Nixon aides considered at one point setting up their own counterpart organization.

Days after the Watergate break-in, both Democrats and Republicans contacted Intertel to request help. Both sides were turned down.

A spokesman for the agency said yesterday that Intertel has never been asked to investigate Chappaquiddick.

Arriving late at the Warner Theater for the opening of "The Best Little Whorehouse in Texas" Wednesday night, Mayor Marion Barry's wife, Effi, stood patiently in the dark behind ushers for a while, waiting for a chance to be seated.

Apparently growing warm, she shed her beige-and-white mink jacket and walked over to a man who had been standing against the wall when she came in.

"Here, hold this," she said, and returned to her place.

He held it.