"I did a lot of research. I had to experiment," James J. Lee told the producer, according to recordings played on NBC's "Today" show this morning.
The producer, Robert Rivas, called the Discovery Channel on Wednesday afternoon to confirm reports about the gunman. Much to his surprise, Lee answered the phone.
"I have a gun, and I have a bomb. I have several bombs strapped to my body ready to go off," Lee told him. "I have a device that if I drop it, if I drop it, it will f------ explode."
Lee entered the Discovery Channel building in Silver Spring, Md., around 1 p.m., armed with a gun and wearing metal canisters that appeared to be explosive devices, police said.
"We heard three gunshots around 1:20 [p.m.]," a Discovery Channel employee who spoke on condition of anonymity told AOL News.
The gunman took two Discovery employees and a security guard hostage in the lobby. The rest of the building, including about 1,900 employees and a day care center on the first floor, was evacuated.
"The tone of his voice indicated that he was someone who was anxious, who wanted to be heard, so I was not taking anything for granted," Rivas said on the "Today" show. "He wanted to have his story told, at least as far as I could tell."
Rivas said Lee sounded calm and did not make any threats during their conversation. When asked how long he had been working on his bombs, Lee said, "Three weeks or a month."
When asked if his actions had helped prepare him for what he was doing, Lee said, "Oh yeah. Everything I do in life, everything one does in life, prepares you for what you are going to do."
Moments later, Rivas heard a phone ring in the background and Lee abruptly ended the call.
Lee's calm demeanor began to change once police started to negotiate with him.
"I would characterize him as very angry throughout our conversation, although he had a wide range of emotions," Montgomery County Police Chief Tom Manger told the "Today" show. "He hung up on us a couple of times, but we very quickly got him back on the phone. Our goal was to try and get through this as safely as possible."
Lee, 43, was originally from Maui, the second-largest of the Hawaiian islands. Former friends and classmates from Lahainaluna High School described him as a kind person, who was sometimes picked on by other kids.
"People always thought of him being a loner, and he did get picked on a lot but he also laughed a lot," former classmate Raynette Romo told Honolulu's KHON News 2.
"It wasn't like you could bully him and he would go on the side and start crying," Romo said.
An unidentified friend and former co-worker told KHON that Lee's demeanor began to change following the death of his parents.
"He went from being a full on religious person carrying his Bible and stuff and preaching to everybody to completely flipped around and basically hating God because God didn't save his mother," the friend said.
Lee was also known throughout school as someone who wanted to save the planet, Romo said.
"He was going to save the Earth, and if it was his way to do his last breath to save Earth, this is what he did."
Lee sold several properties that he had inherited from his parents and relocated to San Diego. While there, he started his campaign against the Discovery Channel, accusing them of promoting overpopulation. Lee spent about $30,000 on full-page advertisements in newspapers, KGMB news in Honolulu reported.
In February 2008, Lee protested in front of the Discovery Channel building. During the demonstration, he threw fistfuls of cash in the air. When police arrested him for disorderly conduct, they found more than $20,000 stuffed in his pockets.
Following his arrest, a judge issued a ruling, barring Lee from coming within 500 feet of the Discovery Channel building, Maryland's Gazette newspaper reported.
Lee also allegedly underwent a mental health evaluation in 2008. "I told [the psychiatrist] my idea of saving the planet," Lee was quoted in the Gazette. "They couldn't find anything wrong with me."
Not long after that arrest, Lee held a contest offering $200,000 worth of Hawaiian real estate and $10,000 in cash for the best TV show idea to save the planet.
"This is the Save the Planet Essay Contest that was stopped with my arrest, before I could find a winner in front of the Discovery Channel protest in Silver Spring Maryland," Lee wrote on a website registered to his name.
Lee's anger with the Discovery Channel's programming escalated over time, and he posted an angry rant on his website.
"Stop all shows glorifying human birthing on all your channels and on TLC," read one of the demands on the now defunct site.
Lee also stated on his website that he was inspired by "My Ishmael," a 1997 book by Daniel Quinn of Houston.
According to Amazon.com, the book is about a telepathic ape "who dispenses ecological wisdom about the possible doom of humankind."
Speaking about the siege with KTRK-TV, Quinn said he was unaware Lee was a fan and had never heard of him before Wednesday.
"I have not encountered him before," Quinn said, adding, "He and I agree together that we see our population growth is a disaster for us, but his idea that population should halt immediately and human birth is a disaster is quite separate from mine."
Discovery Channel spokesman David Leavy told CNN that company officials were familiar with Lee but "did not take his threats or demands seriously."
Wednesday's siege ended shortly before 5 p.m. A police sniper shot Lee dead when he pulled out a handgun and pointed it at one of the hostages, Manger said.
In a statement later, Discovery Communications praised employees for "courage, compassion and cooperation" throughout the situation.
"Discovery thanks the Montgomery County Police and Fire & Rescue and other state and federal safety personnel whose quick thinking and fast action ensured the safety of the employees and children in the building. ... The events of today showed the strong heart of the Discovery family."
The investigation is ongoing today, but police say they believe Lee was acting alone.