A jury in a civil suit brought by the family of the Rev. Dr. Martin Luther King Jr. decided today that a retired Memphis cafe owner was part of a conspiracy in the 1968 killing of Dr. King.

The jury's decision means it did not believe that James Earl Ray, who was convicted of the crime, fired the shot that killed Dr. King.

After four weeks of testimony and one hour of deliberation, the jury in the wrongful-death case found that Loyd Jowers as well as ''others, including governmental agencies'' had been part of a conspiracy. The jury awarded the King family the damages they had sought: $100, which the family says it will donate to charity.

The family has long questioned Mr. Ray's conviction and hoped the suit would change the legal and historical record of the assassination.