Ted Kaczynski conducted a nationwide bombing campaign against universities and airlines from 1978 to 1995, killing 3 and injuring 23. He was arrested in 1996 after his brother recognized his writing style in his manifesto.
In September and October 1982, seven people in the Chicago area died after taking Tylenol capsules laced with potassium cyanide. The case led to tamper-evident packaging becoming an industry standard. The killer was never identified.
Dennis Rader, known as BTK (Bind, Torture, Kill), murdered ten people in Wichita, Kansas, between 1974 and 1991. He taunted police with letters for decades before his arrest in 2005 — over 30 years after his first murders.