Police in Minneapolis say a man known as "Umbrella Man", seen damaging property in the city during the Black Lives Matter protests, has links to white supremacy groups.
People took to the city's streets following the death there in May of George Floyd, an unarmed black man.
Police say Umbrella Man helped turn the largely peaceful protests violent.
Footage of the man wearing a mask and carrying an umbrella while smashing shop windows went viral online.
In the video, taken on 27 May, Umbrella Man can be seen breaking the windows with a hammer as people approach him trying to get him to stop. He then walks away from the scene.
Police said he also sprayed a message on the doors of the store.
It sparked questions as to who the man was and his motives.
Violence broke out in the city during the protests and the National Guard were called in after looting was reported and buildings were set on fire.
Police claim that the man's actions were a catalyst for the violence. The AutoZone store he was seen damaging in the video was later set on fire.
Erika Christensen, Minneapolis police investigator, said in a search warrant affidavit filed on Monday: "This was the first fire that set off a string of fires and looting throughout the precinct and the rest of the city."
The affidavit aims to get access to the man's mobile phone records for that day to establish where he was at the time of the incident.
Who is Umbrella Man?
He has not been named by local media as he has not been formally charged with a crime.
Minnesota police extensively searched through video footage of the violence to try to identify the man but had no luck.
According to the Star Tribune, the man was identified following an email tip-off. The email claimed the man was a member of the Hells Angels biker gang.
An investigation found that the man was also connected to the Aryan Cowboys, a prison biker / street gang. The Anti-Defamation League identifies them as a white supremacist group based primarily in Kentucky and Minnesota.
A search warrant by Minneapolis Police claims that the man has previous convictions for domestic violence and assault.
It was these previous arrests that officers claim helped them identify the man. They compared images taken from the incident in Minneapolis to previous booking photos.
The warrant claims that the man's size and eye, nose and brow area match that of Umbrella Man.
It is also alleged that the man was involved in an incident last month in which a Muslim woman was confronted by a motorcycle group wearing Aryan Cowboy leather vests.
After footage from the Minnesota protests was released online, there were many theories as to who Umbrella Man might be.
The St Paul Police Department was forced to issue a statement and a video denying that he was one of their officers.
Police Chief Todd Axtell said: "We knew right away that our officer was not involved in instigating the unrest in Minneapolis because we knew exactly where he was at the time - and he was in St Paul.
"This type of disinformation can jeopardise the officer's reputation and safety, and chip away at the trust this police department has worked so hard to build with its community," he added.