Robert E Crimo III, 21, was arrested by police hours after shots were fired into the crowd during the celebrations in the Chicago suburb of Highland Park.

Accounts that appear to belong to Crimo posted a number of violent and strange videos online, including crudely drawn animations of a violent shooting.

Scene of the shooting

The video showing Central Avenue, where the shooting took place, was filmed almost a year before the attack.

It appears to have been filmed early in the morning and shows the street empty apart from American flags fluttering in the wind.

Crimo edited it into a longer video that shows him smoking while looking at an American flag at half-mast over a memorial.

In the video, he wears a clear backpack. These bags have been adopted by some American schools in a bid to combat school shootings because they make it harder to hide a gun.

The song Spirit in the Sky accompanies the video and begins with the lyrics "When I die and they lay me to rest/ Gonna go to the place that's the best."

'My actions will be valiant'

A second video, uploaded in October last year, combines a number of his videos into one.

It is being widely referred to as a possible video manifesto by those analysing his online trail because it includes a recorded audio message from him.

In the rambling voiceover, he says: "Like a sleepwalker, I am breaking through... my actions will be valiant and my thought is unnecessary. I know what I have to do."

In the background, a newspaper clipping on the wall marks the death of Lee Harvey Oswald, the man who shot US President John F Kennedy in 1963.

Oswald notoriously fired upon the passing presidential parade from above as he hid on the sixth floor of a building. Similarly, the person who carried out the mass shooting in Chicago is believed to have fired from the rooftop of a building down on to the parade.

Crimo's reference to the former president's assassin appears to be part of a wider interest in presidents and patriotism.

He uploaded a video of himself in 2020 waiting for Donald Trump to land in Air Force One and captured the moment the president at the time drove past as part of a motorcade. There is also a photo of him draped in a Trump flag and attending a rally for the former president.

American flags feature in a number of his archived videos. Crimo is an aspiring rapper and in one of his music videos he holds an American flag behind him after making allusion to school shootings.

Another video uploaded in 2020 features a reference to "enemies in the US".

In it, Crimo films himself staring and close-up to the camera during a remix of people speaking and music.

At the end, he suddenly blinks repeatedly as the recording asks "as you see it, who and what are the enemies of freedom in the US?"

'Robert Crimo archive'

This content uploaded by Crimo was easily findable, despite social media platforms taking swift action to remove his accounts.

He appears to have deliberately created an archive of content that would be simple to find with basic internet search skills.

Crimo used the stage name Awake. He made multiple accounts under his different names and set up at least two blogs that indexed his content.

A specific YouTube account under a third name was also created. Videos uploaded to that channel were dated and give the label "Robert Crimo archive".

He also created back-ups of his content by duplicating many of his videos and photos across different platforms and accounts.

Some of the content includes jokes, some of which appear to have been designed to taunt or fool those looking for answers.

At the end of one uneventful 18-minute long video of him building a cabin next to his family home he says "Goodbye, Mr FBI agent".

Crimo's motive for building his archive is unknown.

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