LOS ANGELES—A legal battle has broken out over who owns 17 never-exhibited Martin Ramirez drawings, the Los Angeles Times reports. Maureen Hammond, a retired art and special education teacher, sued Friday in Los Angeles Superior Court to prove that the works are hers. Hammond had planned to sell the works at auction in September, although the sale has since been called off amid litigation.

Hammond contends that she was pursuing a master's in art therapy at Cal State Los Angeles in 1961 when she wrote to Tarmo Pasto, a psychology specialist in the use of art to treat the mentally ill. Pasto responded with information and enclosed the 17 drawings as a gift.

But two of Ramirez's grandchildren sued on behalf of the late Mexican artist's estate in U.S. District Court in New York on Monday. They are hoping to recover the drawings and claim that Hammond "concealed her possession of the works for over 40 years, until, motivated by the rapidly escalating value of Ramirez's work," she arranged the auction.

Hammond's attorneys say the case could hinge on whether Ramirez was legally competent under California law and capable of giving his artworks as a gift to Pasto.

Ramirez emigrated to the U.S. in 1925 from Mexico. He was a self-taught artist who, diagnosed as a catatonic schizophrenic, spent most of his adult life institutionalized in mental hospitals in California until his death in 1963. In January 2007, the American Folk Art Museum in New York staged a major retrospective of his work, the first of its kind in the U.S. in more than 20 years.