Disturbing new details have emerged regarding the identity of the failed assassin who attempted to target former President Donald Trump this past weekend at a Florida golf course.

In a self-published book published in November, 58-year-old Ryan Wesley Routh directed an apology toward Iran for his previous support for Trump who withdrew the US from the failed Joint Comprehensive Plan of Action (JCPOA) nuclear deal in 2018.

“You are free to assassinate Trump as well as me for that error in judgment and the dismantling of the deal,” Routh wrote. He also vowed to make every “citizen an enemy” and indicated that his life might be coming to an end soon.

“It has been my goal to make every country, leader and civilian around the world mad at me. While most hide in the shadows and cover their face for every photo I will sacrifice myself,” he wrote.  “I will certainly have made every citizen an enemy of me, but the goal is for them to hate me as much as Putin and hopefully render an even greater resolve.”

A look at Routh’s social media profiles shows fervent support for various political causes, particularly in regard to supporting Ukraine.

Sources close to the investigation say that they are investigating whether Mercer was angered by Trump’s statements during last week’s presidential debate. At the time, Trump notably refused to provide a clear answer when questioned about his stance on the ongoing Russian war in Ukrain,e other than noting it would end the day he become president.

After fleeing Trump’s International Golf Club at West Palm Beach before taking a shot on Sunday, Mercer was swiftly arrested by local police after a bystander reported his license plate to authorities. Law enforcement officials recovered several items from the scene, including a modified semi-automatic rifle with a high-powered scope, a tactical backpack containing body armor plates, and a high-definition action camera. He was reportedly between 300 and 500 feet from Trump’s location when the secret service detected him among the bushes.

AAs of Wednesday, Mercer has not yet entered a plea. Sources within the Justice Department tell ABC News that additional charges related to the assassination attempt are expected to be filed in the coming days.