The ex-CIA scientist brothers perfecting Halloween

Jeff and Brian Park spent 40 years working in secret at a CIA lab - but science is just one part of their lives

Crowley Place is a sleepy street in the Waynewood area of south Alexandria, Virginia, a suburb 30 minutes from DC. The unassuming homes are well-tended, and it's a quick walk to six different churches.

But each year at Halloween the police shut down the street as thousands of visitors flock to the area. It's all due to two ageing brothers who spent 40 years working together in secret at a laboratory in the CIA.