His uncle said he “saw no signs of trouble”.
The mayor said she remembers him as “just a little boy” when she knew him as a Cub Scout.
Local police said that he wasn’t even on their radar.
But a close look at Robert Crimo’s online presence tells a very different story.
Across multiple platforms, the 21-year-old often posted disturbing and violent videos including one of a beheading.
The amateur rapper, who goes by the stage name “Awake the Rapper”, celebrated death and glamourised school shootings in one of his music videos, culminating in the gunman being shot dead by police.
There’s also the unexplained obsession with the number 47 – which is the date for July 4 backwards.
Then, on the morning of Independence Day, this obsession with violence appears to have left the online world and entered the real lives of innocent families, friends and locals who had turned out to watch the July 4 parade.
Investigators said that Mr Crimo, disguised in women’s clothing and armed with an AR-15, went to the parade route and scaled the roof of a nearby building.
He then unleashed a hail of more than 70 rounds of bullets into the crowd of parade-goers and participants below, said officials.
Seven people were killed in the attack and dozens more suffered injuries.
Mr Crimo then managed to escape the scene undetected because he was dressed in women’s clothing.
Hiding in plain sight among the panicked parade-goers fleeing the scene, the suspect allegedly calmly walked home to his mother’s house.
He was arrested hours later when he was spotted driving along a highway in his mother’s car.
Investigators said that Mr Crimo acted alone and had “pre-planned his attack for several weeks”.
He purchased multiple firearms – including the AR-15-style rifle used in the attack, a second rifle found in his vehicle during his arrest and pistols found at his home – prior to the mass shooting.
The motive for the attack is still unknown.
Law enforcement, tech companies and even those close to the suspect are starting to face pointed questions about whether major red flags were missed in the run-up to the attack.
In an interview with NBC’s Today show on Tuesday morning, Mayor Nancy Rotering admitted that his online postings “reflected a plan and a desire to commit carnage for a long time in advance”.
When grilled about warning signs being missed in a press conference on Tuesday, Lake County Major Crimes Task Force Sgt Chris Covelli said investigators were reviewing the videos posted online by Mr Crimo and that they had not been aware of them prior to the July 4 massacre.
“We’ll look at them and see what they reveal,” he said.
On Tuesday, both Spotify and Youtube announced that they had removed all of Mr Crimo’s content from their platforms.
Videos glorifying school shootings and mass violence
Among the trail of disturbing online posts are the music videos he posted on his YouTube account under his rap name Awake the Rapper, with videos glorifying school shootings and mass violence.
One music video sees Mr Crimo set inside a classroom in a school.
He repeatedly raps the lyrics “running out of time” and has his feet up on a desk.
Then, at one point, he reaches one hand into his backpack on the floor by his desk.
The video abruptly stops and cuts to footage of him in the same classroom dressed in tactical gear and a black helmet as eerie laughter sounds overhead.
Bullets are strewn along the floor and the room is in disarray.
At one point, he drapes an American flag over his shoulders.
Several cartoon animation videos are also used to glamourise school shootings.
One of his most recent music videos, titled “Are you Awake”, shows a cartoon figure of a shooter bears a strong resemblance to Mr Crimo with his face tattoos.
The figure is wearing tactical gear and is armed with a rifle, carrying out a mass shooting.
Victims are seen lying on the floor while others hold their hands in the air surrendering.
“I need to just do it. It is my destiny,” the lyrics say.
In another animated video, titled “Toy Soldier”, the character resembling Mr Crimo is seen lying dead in a pool of blood surrounded by heavily armed law enforcement.
Before the platform took his content down, Mr Crimo had more than 16,000 listeners a month on his Spotify page.
Celebrating suicide on Discord
Mr Crimo also used the channel Discord, where he would post on a politics board under his username “SS”.
His last post was in March where he appeared to celebrate suicide in comments about lawmaker Budd Dwyer.
Dwyer famously killed himself live on television during a press conference attended by several members of the media back in 1986.
The Pennsylvania State Treasurer had just been convicted of bribery and was facing 55 years in prison.
Mr Crimo posted a photo of the late lawmaker, with the caption: “I wish politicians still gave speeches like this.”
Other photos of Mr Crimo taken from Discord appear to refer to suicide.
“Cursed image screenshot and send to everyone or commit not alive anymore,” read the caption on one of his selfies.
The Discord channel was also shut down on Monday evening.
Far-right and pro-Trump sentiment
Mr Crimo’s online presence indicates that he harbours something of a far-right and pro-Donald Trump sentiment.
His Discord server name was “SS” – the Nazi group responsible for the murder of millions of Jews in the Holocaust.
Photos shared on social media by Mr Crimo appear to also show that he is a supporter of Mr Trump – who is currently himself the focus of an investigation in Congress over the January 6 Capitol riot.
In one selfie, Mr Crimo was dressed up as the character from “Where’s Waldo” while attending a pro-Trump rally in Northbrook, Illinois, in September 2020.
The photo shows a Trump 2020 flag in the background.
Mr Crimo was also pictured in a Chicago Tribune story about the rally, where the protest was described as “tense” with supporters and counter-protesters facing off against each other.
Another photo circulating online shows Mr Crimo wrapped in a blue Mr Trump flag.
However, the 21-year-old had also liked a video of President Joe Biden.
It has also emerged that Mr Crimo’s father, Bob Crimo, only follows one account on Twitter – an archived account of Mr Trump’s tweets.
Bob Crimo made a failed bid as mayor of Highland Park where he lost out to the current mayor, Ms Rotering.
Footage of attack site
As well as graphic violent content, last year also Mr Crimo posted a video online appearing to scope out the location of the attack.
The footage, posted on his personal blog, shows Central Avenue in Highland Park from on the ground.
Central Avenue was the main street of the parade route.
Other online content sending alarm bells include him allegedly sharing a beheading video to a message board and also making reference to Lee Harvey Oswald – the man who assassinated JFK, reported NBC News.
Obsession with the number 47
Mr Crimo also appears to have a bizarre obsession with the number 47, making repeated references to it on his Twitter account and even having the number tattooed on the side of his face.
The number was also painted on the door of a car that was seen parked outside his family home on Tuesday.
Social media users suggested that the number is “part of his violent fantasy world”, with several pointing to a photo of Mr Crimo wearing a dark suit with a red tie which appeared to closely resemble the character Agent 47 from the shooting video game Hitman.
Other suggestions about the number’s significance is that it spells out the date of July 4 backwards.
The next president would also be the 47th.