He was previously accused of fraud and a hit-and-run as well as making threats and damaging property – but all charges were dismissed.
The 48-year-old German man, believed to be the sole perpetrator in Saturday’s attack, has been identified as Jens R, who was reportedly an industrial designer.
Police are focusing on his apparent mental health problems as they investigate the incident.
The attacker had vaguely announced his suicide plans a week ago in an email to friends, it is claimed, but police would not confirm this.
Twenty people were injured, with some remaining in a critical condition, after he ploughed his grey VW into people outside a bar in the city of Munster.
He then fatally shot himself.
Officials said there were no links to Islamist terrorism.
Inside the van, police found the gun he used as well as illegal firecrackers disguised as a fake bomb and an imitation pistol.
Officers have been searching the man’s four apartments – two in Munster and two in Saxony – as well as several cars.
Those killed have been identified as a 51-year-old woman from Lueneburg county, around 180 miles to the northeast, and a 65-year-old man from nearby Borken county.
The gunman had previously faced three court proceedings in Munster and one in nearby Arnsberg in 2015 and 2016.
Broadcaster NTV reported he had threatened family members with an axe in 2014 and 2015.
German interior minister Horst Seehofer, who visited the crash scene and laid flowers, said “this cowardly and brutal crime has shocked all of us”.
He added: “There are strong indications at the moment that this was a lone perpetrator and that there were no links to the terror scene.”
Armin Laschet, the governor of North Rhine-Westphalia state where Munster is located, has also toured the city.
More from Germany
Men held over ‘plot to attack Berlin half marathon’
Munster residents in shock after sunny day turns gruesome
Two killed as van hits crowded restaurant in Munster, Germany
North Korean rockets fitted with nuclear weapons ‘can reach central Europe’
‘Bookkeeper of Auschwitz’ Oskar Groening dies at age of 96
Angela Merkel secures fourth term in Germany after coalition party approves deal
“This was a horrible and sad day for the people of Munster, all of Germany… and also the people of the Netherlands, who were sitting here and became victims,” he said.
Two of those injured were Dutch, including one in a critical condition.