One of the world's most prolific serial killers Ted Bundy is the focus of an exclusive interview with Bundy's ex-girlfriend who ends her 40-year silence tonight on ABC's 20/20 show

Elizabeth Kendall dated Bundy for several years beginning in 1969 and was briefly engaged to the serial killer during the time it is believed he began his killing spree. In all Bundy confessed to killing 30 women from 1973-1978 however authorities and experts believe there were many more.

Here's a preview of the show which airs on 20/20.