Early investigations by the US authorities have not revealed any connection to terrorism as reports emerged that the suspect may have been fleeing an earlier crime scene before he ploughed his vehicle into parade crowd.
US authorities have not found any terrorism link during initial investigations into the deadly Wisconsin Christmas parade incident in which five people were killed.
The suspect appeared to be fleeing another crime scene when the vehicle sped through the parade route, CNN reported on Monday, citing multiple law enforcement sources.
Although the investigation was in its early stages, authorities have found no connection to terrorism, the sources said.
The initial assessment was established after police investigated into what led a suspect to drive a speeding SUV into dozens of people at the parade.
On the morning after Sunday's carnage, a pink hat, a lone shoe and candy lay strewn across the main thoroughfare in Waukesha, roughly 20 miles (32 km) west of Milwaukee.
Dozens of orange evidence circles were painted on the street and most shops were closed in the city's downtown district.
About 40 people were also injured in the incident.
On Sunday, Waukesha Police Chief Dan Thompson told reporters that one person was in custody and they found the red sport utility vehicle seen plowing into pedestrians.
The FBI is assisting local police in their investigation.
Several media reports, citing law enforcement sources, identified the person in custody as Darrell Brooks, 39.
A search of online court records showed a recent open case involving a 39-year-old person named Darrell Brooks.
According to the court documents, he is charged with restricting or obstructing an officer, bail jumping and battery.
A $1,000 cash bond was posted last week, the records show.