Michael Huber 
CNN
—
Among the documents Donald Trump’s would-be-assassin studied while formulating his plans for an attack on the former president was a public document from the Department of Homeland Security, describing different kinds of improvised explosive devices and the number of explosives needed to inflict casualties over certain distances, a senior law enforcement official told CNN.
The FBI discovered saved images of the fact sheet, titled “IED Attack: Improvised Explosive Devices,” in early searches of Thomas Matthew Crooks’ electronics. While the document from the National Academies and DHS also explains what to do in an IED attack to protect yourself and others, its focus is on the key properties and conditions for using destructive, explosive devices. The document, which is more than a decade old, remains online.
The FBI would not respond to CNN’s questions about what specifically was found on the shooter’s electronics, but the agency said that any questions regarding the DHS document should be directed to DHS.
A DHS official told CNN the department “provides information to the American public on how to protect against a range of potential homeland security threats.” The department, the official added, “cannot speak to the FBI’s investigation” nor “speculate about any documents that may have been found on his devices.”
The document included charts outlining specific types of IEDs, their primary components and amounts of explosives needed to achieve certain blast radiuses. It also notes the practice of placing secondary devices to attack first responders and lists examples of “terrorist IED attacks.”
A footnote at the bottom of the document directs readers to other fact sheets in a series published by DHS and the National Academies, describing the essential tactics for other kinds of attacks including chemical, radiological, or biological.
Details on the IED document come as the FBI on Wednesday released photos of the gun Crooks used to shoot Trump during the July rally in Butler, Pennsylvania, as well as the backpack and two remote-controlled IEDs found in the trunk of his car parked near the rally. FBI officials provided new information related to the shooter’s internet searches in the days before the assassination attempt and outlined how investigators are using those searches to piece together his mindset that day.
“We saw through our analysis of all his – particularly his online searches – a sustained detailed effort to plan an attack on some events, meaning he looked at any number of events or targets,” said Kevin Rojek, the special agent in charge of the FBI’s Pittsburgh Field Office. “And then, when this event was announced, the Trump rally was announced, early in July, he became hyper-focused on that specific event and looked at it as a target of opportunity.”
While Rojek detailed how the shooter saw the Trump rally as a “target of opportunity,” officials have not yet identified a motive and said that Crooks expressed “no definitive ideology.”
Crooks would eventually fire eight shots at Trump from the roof of one of the buildings in the complex, killing one spectator and injuring two others before a Secret Service sniper shot and killed him.
CNN’s Holmes Lybrand contributed to this report.
