James Lee was imprisoned in 2003 after being found with a woman hidden in a hidden compartment in his car trunk, near the San Ysidro border into southern California.
"There I was in a Tijuana hotel being further subjected to more of life's brutality," Lee wrote in his confession, which was uncovered Thursday by ABC News. Lee claimed he had been choked and robbed in Tijuana and was duly forced into servitude to make his way home.
All the hostages were unharmed after the four-hour standoff at the Discovery Channel in which suspected explosives strapped to the gunman's body apparently detonated in a cloud of smoke as he was shot. A bomb disposal robot was sent in to ensure no further explosionsives were undetonated.
Police said SWAT teams had fired on the suspect, who was under video surveillance during hours of tense negotiations, when he pointed his gun at one of the hostages, who appeared to make a break for it.
"At that point our tactical units moved in. They shot the suspect. The suspect is deceased," police chief J. Thomas Manger told reporters.
The suspect was reported to be James Lee, who has a history of protest against the Discovery Channel, and was convicted in March 2008 of disorderly conduct, given six months of supervised probation and a small fine.
Manger acknowledged the gunman "had some history with the folks at Discovery Channel and I believe in fact that he was arrested here a couple years ago."
Lee entered the lobby of the sprawling building at about 1 p.m., waving a handgun with a package and "metallic" canisters strapped to his body, police said.
Bomb disposal experts were rushed to the scene, as the building and the surrounding area were evacuated. Infants were wheeled away in cribs from a day care centre on the first floor of the building.
Police were still investigating reports the gunman fired at least one shot as he stormed into the building, a large complex in the Washington suburb of Silver Spring where some 1,900 people work.
Lee, who had his own Save The Planet protest site, admitted on a Web page attributed to him he had a gripe with the Channel, which is known for its wildlife documentaries as well as military and survivalist programs.
He had a list of demands included that the station "broadcast to the world their commitment to save the planet."
Lee insisted that Discovery "stop encouraging the birth of any more parasitic human infants," cease promoting war and weapons of mass destruction through its technology programming, and promote an end to all immigration.
In his writings on his messageboard Lee called out programs such as Kate Plus 8, 19 Kids and Counting, Deadliest Catch and Mythbusters as being hypocritical, promoting things that hurt the planet while the channel draped itself in the banner of environmentalism.
His previous arrest came after Lee threw thousands of dollars into the air outside the Discovery Channel building in 2008, having paid homeless people and children to protest with him. Lee had taken out full page print ads in local media accusing Discovery of hypocrisy.
He was arrested for littering and creating a disturbance, held for two weeks and put through a pyschiatric evaluation before being senenced to two years probation.
