Birth Sis Looking For 1/2 Bro Born Dec. 1974 "jude", Now "chris"

Here's what I know: my father and his girlfriend at that time had a son named Jude that they placed for adoption. He was born in December of 1974 and was adopted by a family in California who named him Christopher. He lives there now and is married (don't know if he has children). He was in contact with his birthmother, Druscilla, who lives in Florida. She contacted my father but he was too afraid to have contact with my brother. I only found out I had a 1/2 brother about 11 years ago and have wondered about him ever since. He may have been put up for adoption in Illinois. My father's first name is Robert and has red hair. I would love to hear from my brother and get to know him - it's been too long already...