Reinking is scheduled to make his first court appearance on May 7 in Nashville, about 25km away from the Waffle House where police say he opened fire on unsuspecting diners.
Four people were killed - Taurean Sanderlin, 29; Joe Perez, 20; DeEbony Groves, 21; and Akilah Dasilva, 23 - and two others were hospitalised in stable condition, authorities said.
It was the second time in a matter of months that the Antioch community on the city's outskirts was shaken by a mass shooting, following the September attack on a church that ended with one person killed.
"Tragedies like this are a fundamental threat to our way of life in America," Nashville Mayor David Briley, D, said after Reinking's arrest. "Everyone should be able to go to a restaurant or church or school without fear."
Questions still lingered after the Waffle House shooting, including what could have prompted the attack. Police said that after he was arrested, Reinking declined to offer a statement or answer questions, instead requesting a lawyer.
Reinking had still not spoken to investigators as of today, 24 hours after he was arrested, said Don Aaron, a spokesman for the Metropolitan Nashville Police Department.
"The motive is undetermined," Aaron wrote in an email.
Some wondered whether race had again played a role in a horrific shooting, given that Reinking is white and the people he is accused of shooting were black and Hispanic.
More uncertainty also swirled around how someone who had raised so many red flags over the years - drawing the attention of local police, state police, the FBI and the US Secret Service - was still allegedly able to use a gun authorities said he had been barred from possessing and had signed over to his father.
Authorities said the AR-15 used in the Waffle House shooting was among the guns that Reinking had previously said he gave to his father. In the affidavit filed in court, officials said the serial number on the AR-15 - which remained at the Waffle House after the shooting - revealed it was a gun that had been linked to him.
Police records showed that Reinking had a series of increasingly troubled encounters with authorities since 2016.
According to one report, he told police that the pop star Taylor Swift was stalking and harassing him. Another time, police said, he went to a local pool, swam in his underwear and tried to pick fights with lifeguards. The police reports say that the same day, he went to the offices of his father's construction business with a rifle, shouted expletives at employees and then drove away.
In a police report, an officer said Reinking's father, Jeffrey, told police he had taken away his son's firearms - three rifles and a handgun - while he was having problems, but then returned them.
The Tazewell County Sheriff's Office in Illinois, where the 29-year-old suspect lived before relocating to Tennessee, said the state police last year asked the office to revoke a card allowing Reinking to possess guns and ammunition in Illinois.
The request came several weeks after Reinking was arrested outside the White House for trying to cross a security barrier, declaring himself "a sovereign citizen" and ignoring orders to stop, according to a District of Columbia police report.
Matthew Espenshade, assistant special agent in charge of the FBI's Memphis division, said yesterday that "every federal resource was brought to bear" in Reinking's case after his arrest at the White House and an assessment the bureau carried out.
"We were able to effectively neutralise what we felt was the threat at the time by ensuring that he did not have the ability to purchase or own weapons and that those weapons were taken," Espenshade said.
Illinois state records show that Reinking signed his four guns over to his father on August 24, 2017. Police said Reinking's father told authorities that he eventually gave the guns back to his son.
Federal officials said Jeffrey Reinking could potentially face charges for the transfer.
