The federal investigation of the shooting of civil rights leader Vernon Jordan is focusing on convicted sniper Joseph Paul Franklin because he has been placed in Fort Wayne, Ind., about the time of last May's attack and because a cellmate claims Frankling bragged to him about the shooting, sources said yesterday.

The head of the FBI office in Indianapolis said at a news conference yesterday that the Franklin investigation will be a high priority in his office.

"I'm optimistic that we can come to a conclusion in the case," said John C. McGinley, new special agent in charge of the office. He refused to say whether Franklin was the prime suspect in the case, as The Washington Post reported Thursday.

A spokesman for the office added later: "Here's a guy that's been around the country shooting people, especially mixed couples, so we'd be foolish if we didn't look at him pretty strongly."

Franklin faces sentencing Monday in Salt Lake City on federal convictions stemming from the killings of two black men last August, and was charged Wednesday with double murders in Oklahoma City and Indianapolis.

The FBI officials in Indianapolis yesterday did not explain why Franklin is now a key suspect in the Jordan case, but other sources said a cellmate who was as key witness in Franklin's federal trial in Salt Lake City last month told authorities that the 30-year-old Alabama drifter boasted of the Jordan shooting in Fort Wayne as well as the sniper attacks on several other blacks. s

In addition, the sources said, authorities recently discovered a witness who has identified Franklin as being in Fort Wayne about the time Jordan, president of the National Urban League, was shot.

Franklin's attorney, Robert L. Van Sciver of Salt Lake City, has accused Justice Department officials of trying to coerce his client into confessing the Jordan shooting by threatening him with the filing of the other murder charges by the state officials. Utah, Indiana and Oklahoma all permit the death penalty for murder convictions.