The Daily Telegraph reported that he had recently been kicked out of university.
Khater was forced out of Coventry University after failing the first year of his accountancy course.
Khater was held on "suspicion of terrorist offences" and also charged with attempted murder.
Sources have confirmed that he was granted asylum in Britain a decade ago and was granted citizenship earlier this year.
He had previously studied electrical engineering at Sudan University of Science and Technology in Khartoum.
Before that he went to school in Wad Madani, a town in east central Sudan, where his parents were sorghum farmers.
About four months ago he moved out of a flat over an internet cafe where he had been staying alone in the Sparkbrook area of Birmingham.
Police have been to the Bunna Internet cafe and taken away a computer, and other items in plastic bags.
Khater moved to another flat in Hall Green, Birmingham but was reportedly seen regularly at the internet cafe, including on the day before the attack.
According to people there, he rarely conversed. One said Khater's father and brother had died within a short space of time. His former landlord said he always paid his rent on time.
"Given that this appears to be a deliberate act, the method and this being an iconic site, we are treating it as a terrorist incident, and the investigation is being led by officers from the Counter Terrorism Command," said Neil Basu, police assistant commissioner.
Prime Minister Theresa May's office said Britain's counterterrorism police are carrying out 676 live investigations, up from more than 500 in March. The prime minister's office said that "13 Islamist plots and four plots by far-right extremists had been foiled in the past 18 months."
Several witnesses told British news media that the crash appeared to be intentional. The silver Ford Fiesta sideswiped cyclists and pedestrians. The London Ambulance Service said two people were hospitalized. A third suffered minor injuries.
The Palace of Westminster, where Parliament convenes, bolstered security around the buildings in March 2017, after Khalid Masood drove his car into crowds along Westminster Bridge, killing four people. In that attack, Masood leaped from his smashed car with a knife and began slashing at police and passersby. He killed one policeman before he was shot and killed by armed officers.
Footage from a rooftop video camera of the latest attack showed the suspect's car clipping cyclists and narrowly missing pedestrians, jumping a curb and weaving toward the barriers, before crashing outside the Parliament building, across the street from Westminster Abbey. Parliament is on summer recess.
Police immediately surrounded the car, which was travelling fast enough to deploy its air bags upon collision. Photographs taken at the scene show police surrounding a silver sedan, with automatic weapons pointed inside the car.
The 2017 vehicular and knife attack at Westminster by Masood, a 52-year-old Muslim convert born in Britain under the name Adrian Russell Ajao, was an attempt, according to police, to carry out "Islamist-related terrorism" that was "inspired" by Islamist militant groups overseas, but not directed by them.
In a WhatsApp message sent moments before the 2017 assault, Masood declared he was waging religious war on behalf of Muslim countries in the Middle East under attack by the West.
- additional reporting Daily Telegraph
