Chapman attended York University in the early 1990s and later studied book and magazine publishing at Centennial College. He went on to serve as Editor at History Magazine and as Director of the Toronto Architectural Conservancy board.

Chapman first published Infiltration in 1996. In total, 25 issues were published ... covering such urban exploration topics as the navigation of storm drains, evading hotel security and adventuring through abandoned military shelters. He also launched infiltration.org, an online version of the zine, in 1996.

His book, Access All Areas: a user's guide to the art of urban exploration, was published in July 2005, shortly before his death. The book serves as a how-to-guide to urban exploration ... covering topics from basic stealth and concealment, to social engineering techniques to ethics. Chapman is credited with coining the term "credibility prop", which describes a device, uniform, piece of equipment or other appurtenances used solely to reduce suspicion if one is encountered in a normally restricted area. A specific example of "credibility prop" is simply being wet (wetness being a good credibility prop for infiltration of a hotel pool) A Guide to Getting Wet in Toronto Hotels.

Jeff and his wife Liz were both interview subjects in the film The Documentary as participants in the Toronto BBS community and other early online communities. He is credited under the handle Milky, though he was also known as Milky Puppy online.