Kyle Odom, the former US Marine suspected of shooting a prominent Idaho pastor on Sunday, believed a Martian race was taking over the world and he needed to take drastic actions to get people to pay attention. He also swears he isn't crazy.

Odom was arrested Tuesday night outside the White House for throwing "unknown material" over the south fence, the US Secret Service said in a statement. The arrest ends a two-day manhunt for Odom, who authorities believe shot evangelical Pastor Tim Remington in Coeur d'Alene, Idaho, on Sunday.

Hours before his arrest, Odom distributed what appeared to be a rambling manifesto to several news outlets. The 21-page document, which Washington television channel KHQ posted online, provides insight into the troubled mind of the man at the center of a bizarre saga of events that unraveled over the previous three days.

"If you talk to me in person, you will see that I'm not crazy at all," the manifesto reads. "The Martians are just so good at hiding in plain sight that no one would know they exist unless they revealed themselves."

On Sunday, Odom allegedly opened fire on Remington, who survived, in the parking lot of the Altar Church in Idaho. The shooting immediately drew national attention because the pastor had delivered the opening prayer at a Ted Cruz campaign event just 24 hours prior. Authorities issued an arrest warrant for Odom, who had fled the scene, and embarked on an extensive search for him.

Odom turned up on Tuesday evening in Washington, where the Secret Service — the federal agency in charge of protecting the president — took him into custody after agents discovered him throwing items over the White House fence.

Earlier on Tuesday, a message was posted on Odom's Facebook account saying that he had to shoot Remington because he was a Martian and "the reason my life was ruined," reported local television station KXLY.

"I will be sharing my story with as many people as possible. I don't have time right now, they are chasing me," the cryptic Facebook message read. "I shot Pastor Tim 12 times, there is no way any human could have survived that event. Anyway, I have sent my story to all the major news organizations. I have no time, I have to go."

Many speculated that the shooting was politically motivated, due to the connection between Remington and Cruz. But Odom's manifesto, which Coeur d'Alene Police Chief Lee White said he sent to several news outlets on Tuesday, does not mention Cruz. Instead, it reveals the desperate ramblings of someone who appeared to be struggling with severe mental illness.

In the manifesto, Odom details how his life had been ruined by an "intelligent species of amphibian-humanoid from Mars," and that he had tried to notify the government about it but had been ignored. He also implies he shot Remington, and another pastor at the church. Police Chief White said that the second pastor is now under police protection.

Odom describes the characteristics of the Martian race as "hypersexual, hyperaggressive, and paranoid." They are responsible for the "God myth," he writes, and for making humans believe there is a heaven and hell. "Earth is as close to heaven we'll ever get and we are letting the Martians destroy it."

The document also includes several careful drawings of alien figures with green and yellow protruding eyes. Circled below one of the drawings was a description that read, "The only part I really saw was the eyes."

Odom says he has struggled with the Martians for over a year and contemplated suicide several times. Police Chief White said on Monday that Odom had a history of mental illness but did not elaborate on the nature of the illness.

Remington apparently knew Odom, according to local television channel KHQ, although it is not clear what the exact nature of their relationship was. In addition to being a pastor at Altar Church, Remington ran a faith-based drug and alcohol treatment rehabilitation facility, and counseled prison inmates. Part of the rehabilitation program Remington ran involved allowing addicts to stay at his home with his family, and he apparently had been threatened by some of the people he had worked with in the past, according to the local Spokesman-Review newspaper.

The end of the document is addressed to President Obama — whom Odom personally thanks for his service to the country — before including a list of "noteworthy Martians." The list features the names of 50 members of Congress and more than two dozen Israeli politicians. After attempting to notify the President about the existence of the Martians, Odom wrote, "my last resort was to take actions to bring this to the public's attention. I hope something good comes of it. Just realize that I'm a good person and I'm completely innocent."