Codiscovered the double helix By Mark Feeney, Globe Staff *|* July 30, 2004 Francis Crick, who with James D. Watson discovered the double helix structure of the DNA molecule in 1953 -- one of the 20th century's most celebrated scientific breakthroughs -- died Wednesday in a San Diego hospital. He was 88 and had colon cancer. The importance of their discovery can hardly be overstated. It all but created the field now known as molecular biology, and led to an understanding of the genetic basis of diseases, which has revolutionized the search for drugs and other treatments. He was one of the great scientists of research in medicine in the 20th Century. My prayers go out to his family and friends. May he rest in peace.