Why did Charles Guiteau kill US president James Garfield?

WARNING: This article contains spoilers from Death By Lightning.

Death By Lightning has dropped on Netflix but what is the reason behind Charles Guiteau killing President James Garfield?

In 1881, James Garfield (played by Michael Shannon) was elected to represent the Republican party before being named as the President of the United States.

Meanwhile, failed lawyer Charles Guiteau (Matthew Macfadyen) struggled to find a purpose until he decided he would "help" Garfield to become President by rallying up support.

It was then in July 1881, around six months after his presidency, that Garfield was shot by Guiteau twice at the Baltimore and Potomac Railroad station in Washington, DC and died two months later.

So how did Guiteau go from being one of Garfield's biggest supporters to the man who killed him?

Guiteau believed that he was truly vital to Garfield becoming President during the election campaign, especially after a short speech he wrote and delivered at a rally.

And so he started petitioning for a diplomatic post, specifically the French consulship, a position that Guiteau should have despite having no experience.

Throughout the campaign and in the months after Garfield began his duties in the White House, Guiteau continued to stalk not only the President but other prominent figures.

He often tried to speak with the Secretary of State James Blaine (Bradley Whitford) and Vice President Chester Arthur (Nick Offerman) who he felt he had a connection with.

Guiteau continuously tried to meet with them in a bid to be hired for a Government position but Blaine eventually had enough and told him point blankly it wasn't to happen and he shouldn't return.

This led to something snapping in Guiteau who made the decision that Garfield was no longer fit to be President.

In the Netflix drama's third episode, he is seen to be writing a letter to Garfield, stating: "I have been trying to be your friend but I do not think that you appreciate it.

"You were supposed to be the one who finally changed things. A president for the people.

"I shouted your name in the streets for months until my voice ran hoarse. I fought for you, desperately. But you lied to us."

He then goes on to say: "I helped sell you. The worst mistake I ever made in my life was believing in you."

In reality, Guiteau wrote numerous letters ahead of the assassination, including one where he said if he didn't fire Blaine then both him and the Republican Party would "come to grief".

During the Netflix series, Guiteau goes to speak to a priest in a confessional where he states that it was God who has given him a "great and terrible task".

Guiteau also later described the act as an "unfortunate political necessity" and wanted Vice President Arthur to become President, which he did following Garfield's death.

Death By Lightning is available to watch on Netflix.