https://www.reuters.com/article/us-theranos-holmes/theranos-founder-elizabeth-holmes-begins-defense-case-idUSKBN2I420R >SAN JOSE, Calif. (Reuters) -Lawyers for Theranos founder Elizabeth Holmes began to present witnesses in her defense against fraud charges on Friday, but it remained unclear whether the former Silicon Valley executive who once promised to revolutionize the blood testing industry would testify.