Richard T. Mitch, who also used the name Dick Michaels, 65, co-founder of the Advocate, a Los Angeles-based national gay and lesbian newsmagazine. A native of Rochester, N.Y., Mitch earned chemistry degrees from New York's Rensselaer Polytechnic Institute and the University of Notre Dame. After serving in a research position with the Army, Mitch began his journalism career on the Journal of the American Chemical Society, first in San Francisco and later in Los Angeles. He became a gay rights activist after he was arrested in a Los Angeles Police Department raid on a gay bar. Joining the group PRIDE, Mitch became editor of its newsletter, which evolved into the Advocate in 1968. Mitch and two co-founders sold the paper in 1975. On Friday in Syracuse, N.Y., of cancer.