Trump assassination attempt: Suspect's possible 'personal vendetta' among investigators' 4 key questions

Now that alleged would-be Trump assassin Ryan Routh is in custody, the FBI and Florida police will have their hands full unraveling his planning process and what may have motivated him. 

Former NYPD investigator and security expert Patrick Brosnan told Fox News Digital that investigators will need to trawl through a litany of information in the coming weeks, including "all things cellular, online shopping; phone camera images, bank records, email correspondence, recent search engine inquiries, dating app activity, identification of any possible burner phones, footage from … city streets, UPS trucks, Amazon trucks or backup cameras, and all cell tower pings within a fixed distance."

Using this information, investigators will build Routh's profile to answer these questions, according to Gene Petrino, a SWAT commander with nearly three decades in law enforcement and a master's degree in security management.

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1. Did Ryan Wesley Routh act alone? 

Petrino said investigators will obtain warrants to scour Routh's social media and speak with his family and associates to determine whether someone else was involved in planning his assassination attempt on Sunday afternoon or anyone who may have trained him beforehand.

"They're going to look for a potential accomplice or someone who had knowledge and didn't say anything," Petrino said.

The FBI said at a news conference on Monday that it does not have information indicating that Routh acted with anyone else.

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2. What was Routh's motive? 

Through associates and social media, investigators will be searching for what could have motivated the 58-year-old to allegedly take aim at the former president. 

"They're definitely going to be looking into his background and his motive. They're going to pull all the videos they can on him, they're going to be looking at social media accounts, they're going to be talking to neighbors," Petrino said. "They're going to look at what might have motivated him or if he has a personal vendetta."

Routh made a number of political posts on X. Before Sunday's assassination attempt, he called Trump a "buffoon," an "idiot" and a "fool," writing that he had supported Trump in 2016 but came to view that decision as a "a terrible mistake." Routh wrote that Iran should feel "free to assassinate Trump as well as me for that error in judgment."

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He also wrote that he would be willing to "volunteer to fight and die" to assist Ukrainian troops on the front lines. 

Routh is a pro-Ukraine activist who has spent time in the Eastern European country volunteering to raise more support for the nation's military efforts and even sought Afghan veterans who fled from the Taliban to fight in the war, a New York Times report noted.

"I guess if someone is passionate enough to feel like they have to go to another country to defend another country, they might feel the same way about what they feel needs to be done in their country," Petrino said.

3. How did Routh come into possession of a firearm? 

After Routh was spotted and fled the scene of Trump International Golf Course, police recovered a loaded SKS-style rifle equipped with a scope and with the serial number removed. Routh was charged in federal court on Monday with possession of a firearm by a convicted felon and possession of a firearm with an obliterated serial number. 

Routh has a criminal record in North Carolina's Guilford County that stretches back to the 1980s. Charges against him have ranged from writing multiple bad checks to felony firearm possession, possession of a stolen vehicle and multiple counts of possession of a weapon of mass destruction in 2002, specifically, a "binary explosive with a 10-in[ch] detonation cord and a blasting cap." 

"They're going to look into how he got the rifle and whether the rifle was used anywhere else," Petrino said. "He had a conviction of weapons possession before, which usually means you aren't able to get another weapon; how was he able to get another weapon if he was a convicted felon?"

4. How did Routh know where to lie in wait?

Routh arrived outside Trump International Golf Course under the cover of darkness and hid in shrubbery for nearly 12 hours, according to court documents. 

Petrino said authorities need to figure out how he knew where Trump would be and how he scoped out a location with a direct shot at the former president.

"You'd have to have done some footwork to find out where to lay low," Petrino said. "Could he have done that on a computer with Google Maps? Sure. But it seems like there was some planning and thought that went into this. How did he know to go to that spot? The chances of him being in the area, seeing a motorcade and saying, 'That's the president, I'm going to go get him,' are very low."

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"How did this guy get the ability to know where Trump was going to be? It seems to me there may be some kind of either a breach in security or somehow what they thought were secure channels were or there is someone on the inside feeding information," Petrino said.

Fox News Digital's Audrey Conklin contributed to this report.