A convicted felon who claims in a public television documentary that he fixed 12 National Football League games in 1968, 1969, and 1970, appears to be the same man whose testimony in a Florida drug-smuggling case two years ago was belittled by a federal judge, the Associated Press reported yesterday.

AP said the witness was John Charles Piazza III, who testified in the West Palm Beach drug-smuggling trial of reputed crime figure Tom Farese, who was convicted and sentenced to 30 years.

The jury said it relied on taped evidence, not Piazza's testimony. Judge Norman Roettger said of Piazza: "He has admitted just about everything under the sun. I think his testimony is impeached."

Meanwhile, a county supervisor in Los Angeles yesterday called on the Justice Department to launch an investigation into charges that the late Carroll Rosenbloom, owner of the Los Angeles Rams, did not die an accidental drowning death off the Florida coast, but may have been murdered.

Supervisor Kenneth Hahn, who says he was a good friend of Rosenbloom's, also called for a federal investigation into Piazza's charges that organized crime figures fixed 12 NFL games in the 1968, 1969 and 1970 seasons.

Hahn's request followed media reports on material contained in a public television documentary to be broadcast nationally Monday (WETA-TV-26 at 8 p.m.). The documentary is called, "An Unauthorized History of the NFL."