Complex sentence: A mathematical prodigy, he abandoned a promising academic career in 1969, then between 1978 and 1995 killed 3 people, and injured 23 others, in a nationwide bombing campaign that targeted people involved with modern technology.
Split into simpler sentences: A mathematical prodigy, he abandoned a promising academic career in 1969. Between 1978 and 1995, he killed three people and injured 23 others in a nationwide bombing campaign that targeted people involved with modern technology.